2008-05-12 15:20:42 -04:00
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/*
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* trace irqs off criticall timings
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
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*
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* From code in the latency_tracer, that is:
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*
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* Copyright (C) 2004-2006 Ingo Molnar
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* Copyright (C) 2004 William Lee Irwin III
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*/
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#include <linux/kallsyms.h>
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/ftrace.h>
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#include <linux/fs.h>
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#include "trace.h"
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static struct trace_array *irqsoff_trace __read_mostly;
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static int tracer_enabled __read_mostly;
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2008-05-12 15:20:42 -04:00
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static DEFINE_PER_CPU(int, tracing_cpu);
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2008-05-12 15:20:44 -04:00
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static DEFINE_SPINLOCK(max_trace_lock);
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2008-05-12 15:20:42 -04:00
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enum {
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TRACER_IRQS_OFF = (1 << 1),
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TRACER_PREEMPT_OFF = (1 << 2),
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};
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static int trace_type __read_mostly;
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#ifdef CONFIG_PREEMPT_TRACER
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2008-05-12 15:20:51 -04:00
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static inline int
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2008-05-12 15:20:42 -04:00
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preempt_trace(void)
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{
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return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
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}
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#else
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# define preempt_trace() (0)
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#endif
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#ifdef CONFIG_IRQSOFF_TRACER
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2008-05-12 15:20:51 -04:00
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static inline int
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2008-05-12 15:20:42 -04:00
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irq_trace(void)
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{
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return ((trace_type & TRACER_IRQS_OFF) &&
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irqs_disabled());
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}
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#else
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# define irq_trace() (0)
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#endif
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2008-05-12 15:20:42 -04:00
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/*
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* Sequence count - we record it when starting a measurement and
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* skip the latency if the sequence has changed - some other section
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* did a maximum and could disturb our measurement with serial console
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* printouts, etc. Truly coinciding maximum latencies should be rare
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* and what happens together happens separately as well, so this doesnt
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* decrease the validity of the maximum found:
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*/
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static __cacheline_aligned_in_smp unsigned long max_sequence;
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2008-10-06 19:06:12 -04:00
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#ifdef CONFIG_FUNCTION_TRACER
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2008-05-12 15:20:42 -04:00
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/*
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* irqsoff uses its own tracer function to keep the overhead down:
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*/
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2008-05-12 15:20:51 -04:00
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static void
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2008-05-12 15:20:42 -04:00
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irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
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{
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struct trace_array *tr = irqsoff_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu;
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2008-05-12 15:20:44 -04:00
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/*
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* Does not matter if we preempt. We test the flags
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* afterward, to see if irqs are disabled or not.
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* If we preempt and get a false positive, the flags
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* test will fail.
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*/
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cpu = raw_smp_processor_id();
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if (likely(!per_cpu(tracing_cpu, cpu)))
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2008-05-12 15:20:42 -04:00
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return;
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local_save_flags(flags);
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2008-05-12 15:20:44 -04:00
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/* slight chance to get a false positive on tracing_cpu */
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if (!irqs_disabled_flags(flags))
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return;
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2008-05-12 15:20:42 -04:00
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1))
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2008-10-01 13:14:09 -04:00
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trace_function(tr, data, ip, parent_ip, flags, preempt_count());
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2008-05-12 15:20:42 -04:00
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atomic_dec(&data->disabled);
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}
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static struct ftrace_ops trace_ops __read_mostly =
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{
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.func = irqsoff_tracer_call,
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};
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2008-10-06 19:06:12 -04:00
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#endif /* CONFIG_FUNCTION_TRACER */
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2008-05-12 15:20:42 -04:00
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/*
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* Should this new latency be reported/recorded?
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*/
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2008-05-12 15:20:51 -04:00
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static int report_latency(cycle_t delta)
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2008-05-12 15:20:42 -04:00
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{
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if (tracing_thresh) {
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if (delta < tracing_thresh)
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return 0;
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} else {
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if (delta <= tracing_max_latency)
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return 0;
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}
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return 1;
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}
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2008-05-12 15:20:51 -04:00
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static void
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2008-05-12 15:20:42 -04:00
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check_critical_timing(struct trace_array *tr,
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struct trace_array_cpu *data,
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unsigned long parent_ip,
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int cpu)
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{
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unsigned long latency, t0, t1;
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2008-05-12 15:20:44 -04:00
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cycle_t T0, T1, delta;
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2008-05-12 15:20:42 -04:00
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unsigned long flags;
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2008-10-01 13:14:09 -04:00
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int pc;
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2008-05-12 15:20:42 -04:00
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/*
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* usecs conversion is slow so we try to delay the conversion
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* as long as possible:
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*/
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T0 = data->preempt_timestamp;
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2008-05-12 15:20:46 -04:00
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T1 = ftrace_now(cpu);
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2008-05-12 15:20:42 -04:00
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delta = T1-T0;
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local_save_flags(flags);
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2008-10-02 19:23:04 -04:00
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pc = preempt_count();
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2008-05-12 15:20:42 -04:00
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if (!report_latency(delta))
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goto out;
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2008-05-12 15:20:45 -04:00
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spin_lock_irqsave(&max_trace_lock, flags);
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2008-05-12 15:20:42 -04:00
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2008-05-12 15:20:44 -04:00
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/* check if we are still the max latency */
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if (!report_latency(delta))
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goto out_unlock;
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2008-10-01 13:14:09 -04:00
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trace_function(tr, data, CALLER_ADDR0, parent_ip, flags, pc);
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2008-05-12 15:20:42 -04:00
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latency = nsecs_to_usecs(delta);
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if (data->critical_sequence != max_sequence)
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2008-05-12 15:20:44 -04:00
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goto out_unlock;
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2008-05-12 15:20:42 -04:00
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tracing_max_latency = delta;
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t0 = nsecs_to_usecs(T0);
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t1 = nsecs_to_usecs(T1);
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data->critical_end = parent_ip;
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update_max_tr_single(tr, current, cpu);
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max_sequence++;
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2008-05-12 15:20:44 -04:00
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out_unlock:
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2008-05-12 15:20:45 -04:00
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spin_unlock_irqrestore(&max_trace_lock, flags);
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2008-05-12 15:20:44 -04:00
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2008-05-12 15:20:42 -04:00
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out:
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data->critical_sequence = max_sequence;
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2008-05-12 15:20:46 -04:00
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data->preempt_timestamp = ftrace_now(cpu);
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2008-09-29 23:02:41 -04:00
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tracing_reset(tr, cpu);
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2008-10-01 13:14:09 -04:00
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trace_function(tr, data, CALLER_ADDR0, parent_ip, flags, pc);
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2008-05-12 15:20:42 -04:00
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}
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2008-05-12 15:20:51 -04:00
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static inline void
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2008-05-12 15:20:42 -04:00
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start_critical_timing(unsigned long ip, unsigned long parent_ip)
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{
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int cpu;
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struct trace_array *tr = irqsoff_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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if (likely(!tracer_enabled))
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return;
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2008-05-12 15:20:55 -04:00
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cpu = raw_smp_processor_id();
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if (per_cpu(tracing_cpu, cpu))
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2008-05-12 15:20:42 -04:00
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return;
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2008-05-12 15:20:42 -04:00
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data = tr->data[cpu];
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2008-05-12 15:20:55 -04:00
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if (unlikely(!data) || atomic_read(&data->disabled))
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2008-05-12 15:20:42 -04:00
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return;
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atomic_inc(&data->disabled);
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data->critical_sequence = max_sequence;
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2008-05-12 15:20:46 -04:00
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data->preempt_timestamp = ftrace_now(cpu);
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2008-05-12 15:20:42 -04:00
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data->critical_start = parent_ip ? : ip;
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2008-09-29 23:02:41 -04:00
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tracing_reset(tr, cpu);
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2008-05-12 15:20:42 -04:00
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local_save_flags(flags);
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2008-05-12 15:20:42 -04:00
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2008-10-01 13:14:09 -04:00
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trace_function(tr, data, ip, parent_ip, flags, preempt_count());
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2008-05-12 15:20:42 -04:00
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2008-05-12 15:20:55 -04:00
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per_cpu(tracing_cpu, cpu) = 1;
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2008-05-12 15:20:42 -04:00
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2008-05-12 15:20:42 -04:00
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atomic_dec(&data->disabled);
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}
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2008-05-12 15:20:51 -04:00
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static inline void
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2008-05-12 15:20:42 -04:00
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stop_critical_timing(unsigned long ip, unsigned long parent_ip)
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{
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int cpu;
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struct trace_array *tr = irqsoff_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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2008-05-12 15:20:55 -04:00
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cpu = raw_smp_processor_id();
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2008-05-12 15:20:42 -04:00
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/* Always clear the tracing cpu on stopping the trace */
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2008-05-12 15:20:55 -04:00
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if (unlikely(per_cpu(tracing_cpu, cpu)))
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per_cpu(tracing_cpu, cpu) = 0;
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2008-05-12 15:20:42 -04:00
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else
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return;
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if (!tracer_enabled)
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2008-05-12 15:20:42 -04:00
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return;
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data = tr->data[cpu];
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2008-09-29 23:02:41 -04:00
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if (unlikely(!data) ||
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2008-05-12 15:20:42 -04:00
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!data->critical_start || atomic_read(&data->disabled))
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return;
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atomic_inc(&data->disabled);
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2008-05-12 15:20:55 -04:00
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2008-05-12 15:20:42 -04:00
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local_save_flags(flags);
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2008-10-01 13:14:09 -04:00
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trace_function(tr, data, ip, parent_ip, flags, preempt_count());
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2008-05-12 15:20:42 -04:00
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check_critical_timing(tr, data, parent_ip ? : ip, cpu);
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2008-05-12 15:20:42 -04:00
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data->critical_start = 0;
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atomic_dec(&data->disabled);
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}
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2008-05-12 15:20:42 -04:00
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/* start and stop critical timings used to for stoppage (in idle) */
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2008-05-12 15:20:51 -04:00
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void start_critical_timings(void)
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2008-05-12 15:20:42 -04:00
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{
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2008-05-12 15:20:42 -04:00
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if (preempt_trace() || irq_trace())
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2008-05-12 15:20:42 -04:00
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start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
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}
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2008-07-26 09:09:47 -04:00
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EXPORT_SYMBOL_GPL(start_critical_timings);
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2008-05-12 15:20:42 -04:00
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2008-05-12 15:20:51 -04:00
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void stop_critical_timings(void)
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2008-05-12 15:20:42 -04:00
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{
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2008-05-12 15:20:42 -04:00
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if (preempt_trace() || irq_trace())
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2008-05-12 15:20:42 -04:00
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stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
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}
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2008-07-26 09:09:47 -04:00
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EXPORT_SYMBOL_GPL(stop_critical_timings);
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2008-05-12 15:20:42 -04:00
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2008-05-12 15:20:42 -04:00
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#ifdef CONFIG_IRQSOFF_TRACER
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2008-05-12 15:20:42 -04:00
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#ifdef CONFIG_PROVE_LOCKING
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2008-05-12 15:20:51 -04:00
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void time_hardirqs_on(unsigned long a0, unsigned long a1)
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2008-05-12 15:20:42 -04:00
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{
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2008-05-12 15:20:42 -04:00
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if (!preempt_trace() && irq_trace())
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2008-05-12 15:20:42 -04:00
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stop_critical_timing(a0, a1);
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}
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2008-05-12 15:20:51 -04:00
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void time_hardirqs_off(unsigned long a0, unsigned long a1)
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2008-05-12 15:20:42 -04:00
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{
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2008-05-12 15:20:42 -04:00
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if (!preempt_trace() && irq_trace())
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2008-05-12 15:20:42 -04:00
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start_critical_timing(a0, a1);
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}
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#else /* !CONFIG_PROVE_LOCKING */
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/*
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* Stubs:
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*/
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void early_boot_irqs_off(void)
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{
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}
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void early_boot_irqs_on(void)
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{
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}
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void trace_softirqs_on(unsigned long ip)
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{
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}
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void trace_softirqs_off(unsigned long ip)
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{
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}
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2008-05-12 15:20:51 -04:00
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inline void print_irqtrace_events(struct task_struct *curr)
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2008-05-12 15:20:42 -04:00
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{
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}
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/*
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* We are only interested in hardirq on/off events:
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*/
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2008-05-12 15:20:51 -04:00
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void trace_hardirqs_on(void)
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2008-05-12 15:20:42 -04:00
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{
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2008-05-12 15:20:42 -04:00
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if (!preempt_trace() && irq_trace())
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2008-05-12 15:20:42 -04:00
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stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
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}
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EXPORT_SYMBOL(trace_hardirqs_on);
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2008-05-12 15:20:51 -04:00
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void trace_hardirqs_off(void)
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2008-05-12 15:20:42 -04:00
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{
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2008-05-12 15:20:42 -04:00
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|
|
if (!preempt_trace() && irq_trace())
|
2008-05-12 15:20:42 -04:00
|
|
|
start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(trace_hardirqs_off);
|
|
|
|
|
2008-05-12 15:20:51 -04:00
|
|
|
void trace_hardirqs_on_caller(unsigned long caller_addr)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
2008-05-12 15:20:42 -04:00
|
|
|
if (!preempt_trace() && irq_trace())
|
2008-05-12 15:20:42 -04:00
|
|
|
stop_critical_timing(CALLER_ADDR0, caller_addr);
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(trace_hardirqs_on_caller);
|
|
|
|
|
2008-05-12 15:20:51 -04:00
|
|
|
void trace_hardirqs_off_caller(unsigned long caller_addr)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
2008-05-12 15:20:42 -04:00
|
|
|
if (!preempt_trace() && irq_trace())
|
2008-05-12 15:20:42 -04:00
|
|
|
start_critical_timing(CALLER_ADDR0, caller_addr);
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(trace_hardirqs_off_caller);
|
|
|
|
|
|
|
|
#endif /* CONFIG_PROVE_LOCKING */
|
2008-05-12 15:20:42 -04:00
|
|
|
#endif /* CONFIG_IRQSOFF_TRACER */
|
|
|
|
|
|
|
|
#ifdef CONFIG_PREEMPT_TRACER
|
2008-05-12 15:20:51 -04:00
|
|
|
void trace_preempt_on(unsigned long a0, unsigned long a1)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
2008-07-15 09:53:37 -04:00
|
|
|
if (preempt_trace())
|
|
|
|
stop_critical_timing(a0, a1);
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
2008-05-12 15:20:51 -04:00
|
|
|
void trace_preempt_off(unsigned long a0, unsigned long a1)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
2008-07-15 09:53:37 -04:00
|
|
|
if (preempt_trace())
|
|
|
|
start_critical_timing(a0, a1);
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
#endif /* CONFIG_PREEMPT_TRACER */
|
2008-05-12 15:20:42 -04:00
|
|
|
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
/*
|
|
|
|
* save_tracer_enabled is used to save the state of the tracer_enabled
|
|
|
|
* variable when we disable it when we open a trace output file.
|
|
|
|
*/
|
|
|
|
static int save_tracer_enabled;
|
|
|
|
|
2008-05-12 15:20:42 -04:00
|
|
|
static void start_irqsoff_tracer(struct trace_array *tr)
|
|
|
|
{
|
|
|
|
register_ftrace_function(&trace_ops);
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
if (tracing_is_enabled()) {
|
|
|
|
tracer_enabled = 1;
|
|
|
|
save_tracer_enabled = 1;
|
|
|
|
} else {
|
|
|
|
tracer_enabled = 0;
|
|
|
|
save_tracer_enabled = 0;
|
|
|
|
}
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
|
|
|
static void stop_irqsoff_tracer(struct trace_array *tr)
|
|
|
|
{
|
|
|
|
tracer_enabled = 0;
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
save_tracer_enabled = 0;
|
2008-05-12 15:20:44 -04:00
|
|
|
unregister_ftrace_function(&trace_ops);
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
2008-05-12 15:20:42 -04:00
|
|
|
static void __irqsoff_tracer_init(struct trace_array *tr)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
|
|
|
irqsoff_trace = tr;
|
2008-05-12 15:20:55 -04:00
|
|
|
/* make sure that the tracer is visible */
|
2008-05-12 15:20:42 -04:00
|
|
|
smp_wmb();
|
2008-11-07 22:36:02 -05:00
|
|
|
start_irqsoff_tracer(tr);
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
|
|
|
static void irqsoff_tracer_reset(struct trace_array *tr)
|
|
|
|
{
|
2008-11-07 22:36:02 -05:00
|
|
|
stop_irqsoff_tracer(tr);
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
static void irqsoff_tracer_start(struct trace_array *tr)
|
|
|
|
{
|
|
|
|
tracer_enabled = 1;
|
|
|
|
save_tracer_enabled = 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void irqsoff_tracer_stop(struct trace_array *tr)
|
|
|
|
{
|
|
|
|
tracer_enabled = 0;
|
|
|
|
save_tracer_enabled = 0;
|
|
|
|
}
|
|
|
|
|
2008-05-12 15:20:51 -04:00
|
|
|
static void irqsoff_tracer_open(struct trace_iterator *iter)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
|
|
|
/* stop the trace while dumping */
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
tracer_enabled = 0;
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
2008-05-12 15:20:51 -04:00
|
|
|
static void irqsoff_tracer_close(struct trace_iterator *iter)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
/* restart tracing */
|
|
|
|
tracer_enabled = save_tracer_enabled;
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
2008-05-12 15:20:42 -04:00
|
|
|
#ifdef CONFIG_IRQSOFF_TRACER
|
2008-11-15 23:57:26 -05:00
|
|
|
static int irqsoff_tracer_init(struct trace_array *tr)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
|
|
|
trace_type = TRACER_IRQS_OFF;
|
|
|
|
|
|
|
|
__irqsoff_tracer_init(tr);
|
2008-11-15 23:57:26 -05:00
|
|
|
return 0;
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
2008-05-12 15:20:42 -04:00
|
|
|
static struct tracer irqsoff_tracer __read_mostly =
|
|
|
|
{
|
|
|
|
.name = "irqsoff",
|
|
|
|
.init = irqsoff_tracer_init,
|
|
|
|
.reset = irqsoff_tracer_reset,
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
.start = irqsoff_tracer_start,
|
|
|
|
.stop = irqsoff_tracer_stop,
|
2008-05-12 15:20:42 -04:00
|
|
|
.open = irqsoff_tracer_open,
|
|
|
|
.close = irqsoff_tracer_close,
|
|
|
|
.print_max = 1,
|
2008-05-12 15:20:44 -04:00
|
|
|
#ifdef CONFIG_FTRACE_SELFTEST
|
|
|
|
.selftest = trace_selftest_startup_irqsoff,
|
|
|
|
#endif
|
2008-05-12 15:20:42 -04:00
|
|
|
};
|
2008-05-12 15:20:42 -04:00
|
|
|
# define register_irqsoff(trace) register_tracer(&trace)
|
|
|
|
#else
|
|
|
|
# define register_irqsoff(trace) do { } while (0)
|
|
|
|
#endif
|
|
|
|
|
|
|
|
#ifdef CONFIG_PREEMPT_TRACER
|
2008-11-15 23:57:26 -05:00
|
|
|
static int preemptoff_tracer_init(struct trace_array *tr)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
|
|
|
trace_type = TRACER_PREEMPT_OFF;
|
|
|
|
|
|
|
|
__irqsoff_tracer_init(tr);
|
2008-11-15 23:57:26 -05:00
|
|
|
return 0;
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
|
|
|
static struct tracer preemptoff_tracer __read_mostly =
|
|
|
|
{
|
|
|
|
.name = "preemptoff",
|
|
|
|
.init = preemptoff_tracer_init,
|
|
|
|
.reset = irqsoff_tracer_reset,
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
.start = irqsoff_tracer_start,
|
|
|
|
.stop = irqsoff_tracer_stop,
|
2008-05-12 15:20:42 -04:00
|
|
|
.open = irqsoff_tracer_open,
|
|
|
|
.close = irqsoff_tracer_close,
|
|
|
|
.print_max = 1,
|
2008-05-12 15:20:44 -04:00
|
|
|
#ifdef CONFIG_FTRACE_SELFTEST
|
|
|
|
.selftest = trace_selftest_startup_preemptoff,
|
|
|
|
#endif
|
2008-05-12 15:20:42 -04:00
|
|
|
};
|
|
|
|
# define register_preemptoff(trace) register_tracer(&trace)
|
|
|
|
#else
|
|
|
|
# define register_preemptoff(trace) do { } while (0)
|
|
|
|
#endif
|
|
|
|
|
|
|
|
#if defined(CONFIG_IRQSOFF_TRACER) && \
|
|
|
|
defined(CONFIG_PREEMPT_TRACER)
|
|
|
|
|
2008-11-15 23:57:26 -05:00
|
|
|
static int preemptirqsoff_tracer_init(struct trace_array *tr)
|
2008-05-12 15:20:42 -04:00
|
|
|
{
|
|
|
|
trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
|
|
|
|
|
|
|
|
__irqsoff_tracer_init(tr);
|
2008-11-15 23:57:26 -05:00
|
|
|
return 0;
|
2008-05-12 15:20:42 -04:00
|
|
|
}
|
|
|
|
|
|
|
|
static struct tracer preemptirqsoff_tracer __read_mostly =
|
|
|
|
{
|
|
|
|
.name = "preemptirqsoff",
|
|
|
|
.init = preemptirqsoff_tracer_init,
|
|
|
|
.reset = irqsoff_tracer_reset,
|
ftrace: restructure tracing start/stop infrastructure
Impact: change where tracing is started up and stopped
Currently, when a new tracer is selected via echo'ing a tracer name into
the current_tracer file, the startup is only done if tracing_enabled is
set to one. If tracing_enabled is changed to zero (by echo'ing 0 into
the tracing_enabled file) a full shutdown is performed.
The full startup and shutdown of a tracer can be expensive and the
user can lose out traces when echo'ing in 0 to the tracing_enabled file,
because the process takes too long. There can also be places that
the user would like to start and stop the tracer several times and
doing the full startup and shutdown of a tracer might be too expensive.
This patch performs the full startup and shutdown when a tracer is
selected. It also adds a way to do a quick start or stop of a tracer.
The quick version is just a flag that prevents the tracing from
taking place, but the overhead of the code is still there.
For example, the startup of a tracer may enable tracepoints, or enable
the function tracer. The stop and start will just set a flag to
have the tracer ignore the calls when the tracepoint or function trace
is called. The overhead of the tracer may still be present when
the tracer is stopped, but no tracing will occur. Setting the tracer
to the 'nop' tracer (or any other tracer) will perform the shutdown
of the tracer which will disable the tracepoint or disable the
function tracer.
The tracing_enabled file will simply start or stop tracing.
This change is all internal. The end result for the user should be the same
as before. If tracing_enabled is not set, no trace will happen.
If tracing_enabled is set, then the trace will happen. The tracing_enabled
variable is static between tracers. Enabling tracing_enabled and
going to another tracer will keep tracing_enabled enabled. Same
is true with disabling tracing_enabled.
This patch will now provide a fast start/stop method to the users
for enabling or disabling tracing.
Note: There were two methods to the struct tracer that were never
used: The methods start and stop. These were to be used as a hook
to the reading of the trace output, but ended up not being
necessary. These two methods are now used to enable the start
and stop of each tracer, in case the tracer needs to do more than
just not write into the buffer. For example, the irqsoff tracer
must stop recording max latencies when tracing is stopped.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-05 16:05:44 -05:00
|
|
|
.start = irqsoff_tracer_start,
|
|
|
|
.stop = irqsoff_tracer_stop,
|
2008-05-12 15:20:42 -04:00
|
|
|
.open = irqsoff_tracer_open,
|
|
|
|
.close = irqsoff_tracer_close,
|
|
|
|
.print_max = 1,
|
2008-05-12 15:20:44 -04:00
|
|
|
#ifdef CONFIG_FTRACE_SELFTEST
|
|
|
|
.selftest = trace_selftest_startup_preemptirqsoff,
|
|
|
|
#endif
|
2008-05-12 15:20:42 -04:00
|
|
|
};
|
|
|
|
|
|
|
|
# define register_preemptirqsoff(trace) register_tracer(&trace)
|
|
|
|
#else
|
|
|
|
# define register_preemptirqsoff(trace) do { } while (0)
|
|
|
|
#endif
|
2008-05-12 15:20:42 -04:00
|
|
|
|
|
|
|
__init static int init_irqsoff_tracer(void)
|
|
|
|
{
|
2008-05-12 15:20:42 -04:00
|
|
|
register_irqsoff(irqsoff_tracer);
|
|
|
|
register_preemptoff(preemptoff_tracer);
|
|
|
|
register_preemptirqsoff(preemptirqsoff_tracer);
|
2008-05-12 15:20:42 -04:00
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
device_initcall(init_irqsoff_tracer);
|