3c5d92a0cf
Allow the architecture to request a normal jiffy tick when the system goes idle and tick_nohz_stop_sched_tick is called . On s390 the hook is used to prevent the system going fully idle if there has been an interrupt other than a clock comparator interrupt since the last wakeup. On s390 the HiperSockets response time for 1 connection ping-pong goes down from 42 to 34 microseconds. The CPU cost decreases by 27%. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> LKML-Reference: <20090929122533.402715150@de.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
142 lines
3.5 KiB
C
142 lines
3.5 KiB
C
/*
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* arch/s390/kernel/s390_ext.c
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*
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* S390 version
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* Copyright (C) 1999,2000 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Holger Smolinski (Holger.Smolinski@de.ibm.com),
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* Martin Schwidefsky (schwidefsky@de.ibm.com)
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/ftrace.h>
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#include <linux/errno.h>
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#include <linux/kernel_stat.h>
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#include <linux/interrupt.h>
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#include <asm/cputime.h>
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#include <asm/lowcore.h>
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#include <asm/s390_ext.h>
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#include <asm/irq_regs.h>
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#include <asm/irq.h>
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#include "entry.h"
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/*
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* ext_int_hash[index] is the start of the list for all external interrupts
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* that hash to this index. With the current set of external interrupts
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* (0x1202 external call, 0x1004 cpu timer, 0x2401 hwc console, 0x4000
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* iucv and 0x2603 pfault) this is always the first element.
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*/
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ext_int_info_t *ext_int_hash[256] = { NULL, };
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static inline int ext_hash(__u16 code)
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{
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return (code + (code >> 9)) & 0xff;
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}
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int register_external_interrupt(__u16 code, ext_int_handler_t handler)
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{
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ext_int_info_t *p;
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int index;
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p = kmalloc(sizeof(ext_int_info_t), GFP_ATOMIC);
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if (p == NULL)
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return -ENOMEM;
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p->code = code;
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p->handler = handler;
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index = ext_hash(code);
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p->next = ext_int_hash[index];
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ext_int_hash[index] = p;
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return 0;
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}
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int register_early_external_interrupt(__u16 code, ext_int_handler_t handler,
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ext_int_info_t *p)
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{
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int index;
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if (p == NULL)
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return -EINVAL;
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p->code = code;
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p->handler = handler;
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index = ext_hash(code);
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p->next = ext_int_hash[index];
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ext_int_hash[index] = p;
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return 0;
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}
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int unregister_external_interrupt(__u16 code, ext_int_handler_t handler)
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{
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ext_int_info_t *p, *q;
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int index;
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index = ext_hash(code);
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q = NULL;
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p = ext_int_hash[index];
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while (p != NULL) {
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if (p->code == code && p->handler == handler)
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break;
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q = p;
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p = p->next;
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}
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if (p == NULL)
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return -ENOENT;
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if (q != NULL)
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q->next = p->next;
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else
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ext_int_hash[index] = p->next;
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kfree(p);
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return 0;
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}
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int unregister_early_external_interrupt(__u16 code, ext_int_handler_t handler,
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ext_int_info_t *p)
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{
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ext_int_info_t *q;
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int index;
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if (p == NULL || p->code != code || p->handler != handler)
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return -EINVAL;
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index = ext_hash(code);
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q = ext_int_hash[index];
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if (p != q) {
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while (q != NULL) {
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if (q->next == p)
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break;
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q = q->next;
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}
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if (q == NULL)
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return -ENOENT;
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q->next = p->next;
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} else
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ext_int_hash[index] = p->next;
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return 0;
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}
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void __irq_entry do_extint(struct pt_regs *regs, unsigned short code)
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{
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ext_int_info_t *p;
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int index;
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struct pt_regs *old_regs;
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old_regs = set_irq_regs(regs);
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s390_idle_check();
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irq_enter();
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if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
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/* Serve timer interrupts first. */
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clock_comparator_work();
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kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
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if (code != 0x1004)
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__get_cpu_var(s390_idle).nohz_delay = 1;
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index = ext_hash(code);
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for (p = ext_int_hash[index]; p; p = p->next) {
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if (likely(p->code == code))
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p->handler(code);
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}
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irq_exit();
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set_irq_regs(old_regs);
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}
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EXPORT_SYMBOL(register_external_interrupt);
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EXPORT_SYMBOL(unregister_external_interrupt);
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