bac28bfe42
Impact: cleanup on output of branch profiler When a branch has not been taken, it does not make sense to show a percentage incorrect or hit. This patch changes the behaviour to print out a 'X' when the branch has not been executed yet. For example: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 2096 0 0 do_arch_prctl process_64.c 832 0 0 X do_arch_prctl process_64.c 804 2604 0 0 IS_ERR err.h 34 130228 5765 4 __switch_to process_64.c 673 0 0 X enable_TSC process_64.c 448 0 0 X disable_TSC process_64.c 431 Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
313 lines
6.5 KiB
C
313 lines
6.5 KiB
C
/*
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* unlikely profiler
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*
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* Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
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*/
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#include <linux/kallsyms.h>
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#include <linux/seq_file.h>
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#include <linux/spinlock.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/hash.h>
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#include <linux/fs.h>
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#include <asm/local.h>
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#include "trace.h"
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#ifdef CONFIG_BRANCH_TRACER
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static int branch_tracing_enabled __read_mostly;
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static DEFINE_MUTEX(branch_tracing_mutex);
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static struct trace_array *branch_tracer;
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static void
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probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
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{
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struct trace_array *tr = branch_tracer;
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struct ring_buffer_event *event;
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struct trace_branch *entry;
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unsigned long flags, irq_flags;
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int cpu, pc;
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const char *p;
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/*
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* I would love to save just the ftrace_likely_data pointer, but
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* this code can also be used by modules. Ugly things can happen
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* if the module is unloaded, and then we go and read the
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* pointer. This is slower, but much safer.
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*/
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if (unlikely(!tr))
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return;
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raw_local_irq_save(flags);
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cpu = raw_smp_processor_id();
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if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
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goto out;
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event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
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&irq_flags);
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if (!event)
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goto out;
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pc = preempt_count();
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entry = ring_buffer_event_data(event);
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tracing_generic_entry_update(&entry->ent, flags, pc);
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entry->ent.type = TRACE_BRANCH;
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/* Strip off the path, only save the file */
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p = f->file + strlen(f->file);
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while (p >= f->file && *p != '/')
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p--;
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p++;
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strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
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strncpy(entry->file, p, TRACE_FILE_SIZE);
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entry->func[TRACE_FUNC_SIZE] = 0;
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entry->file[TRACE_FILE_SIZE] = 0;
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entry->line = f->line;
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entry->correct = val == expect;
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ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
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out:
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atomic_dec(&tr->data[cpu]->disabled);
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raw_local_irq_restore(flags);
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}
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static inline
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void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
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{
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if (!branch_tracing_enabled)
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return;
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probe_likely_condition(f, val, expect);
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}
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int enable_branch_tracing(struct trace_array *tr)
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{
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int ret = 0;
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mutex_lock(&branch_tracing_mutex);
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branch_tracer = tr;
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/*
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* Must be seen before enabling. The reader is a condition
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* where we do not need a matching rmb()
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*/
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smp_wmb();
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branch_tracing_enabled++;
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mutex_unlock(&branch_tracing_mutex);
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return ret;
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}
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void disable_branch_tracing(void)
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{
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mutex_lock(&branch_tracing_mutex);
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if (!branch_tracing_enabled)
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goto out_unlock;
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branch_tracing_enabled--;
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out_unlock:
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mutex_unlock(&branch_tracing_mutex);
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}
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static void start_branch_trace(struct trace_array *tr)
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{
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enable_branch_tracing(tr);
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}
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static void stop_branch_trace(struct trace_array *tr)
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{
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disable_branch_tracing();
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}
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static int branch_trace_init(struct trace_array *tr)
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{
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int cpu;
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for_each_online_cpu(cpu)
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tracing_reset(tr, cpu);
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start_branch_trace(tr);
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return 0;
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}
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static void branch_trace_reset(struct trace_array *tr)
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{
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stop_branch_trace(tr);
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}
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struct tracer branch_trace __read_mostly =
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{
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.name = "branch",
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.init = branch_trace_init,
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.reset = branch_trace_reset,
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#ifdef CONFIG_FTRACE_SELFTEST
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.selftest = trace_selftest_startup_branch,
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#endif
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};
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__init static int init_branch_trace(void)
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{
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return register_tracer(&branch_trace);
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}
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device_initcall(init_branch_trace);
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#else
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static inline
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void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
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{
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}
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#endif /* CONFIG_BRANCH_TRACER */
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void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
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{
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/*
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* I would love to have a trace point here instead, but the
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* trace point code is so inundated with unlikely and likely
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* conditions that the recursive nightmare that exists is too
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* much to try to get working. At least for now.
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*/
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trace_likely_condition(f, val, expect);
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/* FIXME: Make this atomic! */
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if (val == expect)
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f->correct++;
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else
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f->incorrect++;
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}
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EXPORT_SYMBOL(ftrace_likely_update);
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struct ftrace_pointer {
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void *start;
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void *stop;
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};
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static void *
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t_next(struct seq_file *m, void *v, loff_t *pos)
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{
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struct ftrace_pointer *f = m->private;
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struct ftrace_branch_data *p = v;
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(*pos)++;
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if (v == (void *)1)
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return f->start;
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++p;
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if ((void *)p >= (void *)f->stop)
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return NULL;
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return p;
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}
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static void *t_start(struct seq_file *m, loff_t *pos)
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{
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void *t = (void *)1;
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loff_t l = 0;
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for (; t && l < *pos; t = t_next(m, t, &l))
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;
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return t;
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}
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static void t_stop(struct seq_file *m, void *p)
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{
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}
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static int t_show(struct seq_file *m, void *v)
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{
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struct ftrace_branch_data *p = v;
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const char *f;
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long percent;
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if (v == (void *)1) {
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seq_printf(m, " correct incorrect %% "
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" Function "
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" File Line\n"
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" ------- --------- - "
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" -------- "
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" ---- ----\n");
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return 0;
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}
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/* Only print the file, not the path */
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f = p->file + strlen(p->file);
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while (f >= p->file && *f != '/')
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f--;
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f++;
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if (p->correct) {
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percent = p->incorrect * 100;
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percent /= p->correct + p->incorrect;
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} else
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percent = p->incorrect ? 100 : -1;
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seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect);
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if (percent < 0)
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seq_printf(m, " X ");
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else
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seq_printf(m, "%3ld ", percent);
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seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
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return 0;
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}
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static struct seq_operations tracing_likely_seq_ops = {
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.start = t_start,
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.next = t_next,
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.stop = t_stop,
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.show = t_show,
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};
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static int tracing_branch_open(struct inode *inode, struct file *file)
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{
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int ret;
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ret = seq_open(file, &tracing_likely_seq_ops);
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if (!ret) {
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struct seq_file *m = file->private_data;
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m->private = (void *)inode->i_private;
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}
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return ret;
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}
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static const struct file_operations tracing_branch_fops = {
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.open = tracing_branch_open,
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.read = seq_read,
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.llseek = seq_lseek,
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};
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extern unsigned long __start_annotated_branch_profile[];
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extern unsigned long __stop_annotated_branch_profile[];
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static const struct ftrace_pointer ftrace_annotated_branch_pos = {
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.start = __start_annotated_branch_profile,
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.stop = __stop_annotated_branch_profile,
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};
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static __init int ftrace_branch_init(void)
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{
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struct dentry *d_tracer;
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struct dentry *entry;
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d_tracer = tracing_init_dentry();
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entry = debugfs_create_file("profile_annotated_branch", 0444, d_tracer,
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&ftrace_annotated_branch_pos,
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&tracing_branch_fops);
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if (!entry)
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pr_warning("Could not create debugfs "
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"'profile_annotatet_branch' entry\n");
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return 0;
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}
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device_initcall(ftrace_branch_init);
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