1ce2180498
s390 uses open coded seqcount to synchronize idle time accounting. Lets consolidate it with the standard API. Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
125 lines
3.3 KiB
C
125 lines
3.3 KiB
C
/*
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* Idle functions for s390.
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*
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* Copyright IBM Corp. 2014
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*
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
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*/
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#include <linux/kernel.h>
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#include <linux/kernel_stat.h>
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#include <linux/kprobes.h>
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#include <linux/notifier.h>
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#include <linux/init.h>
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#include <linux/cpu.h>
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#include <asm/cputime.h>
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#include <asm/nmi.h>
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#include <asm/smp.h>
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#include "entry.h"
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static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
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void enabled_wait(void)
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{
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struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
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unsigned long long idle_time;
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unsigned long psw_mask;
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trace_hardirqs_on();
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/* Wait for external, I/O or machine check interrupt. */
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psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
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PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
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clear_cpu_flag(CIF_NOHZ_DELAY);
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/* Call the assembler magic in entry.S */
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psw_idle(idle, psw_mask);
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trace_hardirqs_off();
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/* Account time spent with enabled wait psw loaded as idle time. */
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write_seqcount_begin(&idle->seqcount);
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idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
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idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
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idle->idle_time += idle_time;
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idle->idle_count++;
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account_idle_time(idle_time);
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write_seqcount_end(&idle->seqcount);
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}
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NOKPROBE_SYMBOL(enabled_wait);
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static ssize_t show_idle_count(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
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unsigned long long idle_count;
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unsigned int seq;
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do {
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seq = read_seqcount_begin(&idle->seqcount);
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idle_count = ACCESS_ONCE(idle->idle_count);
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if (ACCESS_ONCE(idle->clock_idle_enter))
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idle_count++;
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} while (read_seqcount_retry(&idle->seqcount, seq));
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return sprintf(buf, "%llu\n", idle_count);
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}
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DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
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static ssize_t show_idle_time(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
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unsigned long long now, idle_time, idle_enter, idle_exit;
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unsigned int seq;
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do {
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now = get_tod_clock();
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seq = read_seqcount_begin(&idle->seqcount);
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idle_time = ACCESS_ONCE(idle->idle_time);
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idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
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idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
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} while (read_seqcount_retry(&idle->seqcount, seq));
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idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
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return sprintf(buf, "%llu\n", idle_time >> 12);
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}
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DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL);
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cputime64_t arch_cpu_idle_time(int cpu)
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{
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struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
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unsigned long long now, idle_enter, idle_exit;
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unsigned int seq;
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do {
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now = get_tod_clock();
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seq = read_seqcount_begin(&idle->seqcount);
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idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
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idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
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} while (read_seqcount_retry(&idle->seqcount, seq));
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return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0;
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}
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void arch_cpu_idle_enter(void)
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{
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local_mcck_disable();
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}
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void arch_cpu_idle(void)
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{
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if (!test_cpu_flag(CIF_MCCK_PENDING))
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/* Halt the cpu and keep track of cpu time accounting. */
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enabled_wait();
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local_irq_enable();
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}
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void arch_cpu_idle_exit(void)
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{
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local_mcck_enable();
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if (test_cpu_flag(CIF_MCCK_PENDING))
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s390_handle_mcck();
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}
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void arch_cpu_idle_dead(void)
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{
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cpu_die();
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}
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