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s390/idle: convert open coded idle time seqcount

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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>
This commit is contained in:
Frederic Weisbecker 2014-11-28 19:23:34 +01:00 committed by Martin Schwidefsky
parent 200e7c0ffb
commit 1ce2180498
2 changed files with 13 additions and 14 deletions
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3
arch/s390/include/asm/idle.h
View File

@ -9,9 +9,10 @@
#include <linux/types.h> #include <linux/types.h>
#include <linux/device.h> #include <linux/device.h>
#include <linux/seqlock.h>
struct s390_idle_data { struct s390_idle_data {
unsigned int sequence; seqcount_t seqcount;
unsigned long long idle_count; unsigned long long idle_count;
unsigned long long idle_time; unsigned long long idle_time;
unsigned long long clock_idle_enter; unsigned long long clock_idle_enter;

24
arch/s390/kernel/idle.c
View File

@ -38,15 +38,13 @@ void enabled_wait(void)
trace_hardirqs_off(); trace_hardirqs_off();
/* Account time spent with enabled wait psw loaded as idle time. */ /* Account time spent with enabled wait psw loaded as idle time. */
idle->sequence++; write_seqcount_begin(&idle->seqcount);
smp_wmb();
idle_time = idle->clock_idle_exit - idle->clock_idle_enter; idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
idle->clock_idle_enter = idle->clock_idle_exit = 0ULL; idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
idle->idle_time += idle_time; idle->idle_time += idle_time;
idle->idle_count++; idle->idle_count++;
account_idle_time(idle_time); account_idle_time(idle_time);
smp_wmb(); write_seqcount_end(&idle->seqcount);
idle->sequence++;
} }
NOKPROBE_SYMBOL(enabled_wait); NOKPROBE_SYMBOL(enabled_wait);
@ -55,14 +53,14 @@ static ssize_t show_idle_count(struct device *dev,
{ {
struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
unsigned long long idle_count; unsigned long long idle_count;
unsigned int sequence; unsigned int seq;
do { do {
sequence = ACCESS_ONCE(idle->sequence); seq = read_seqcount_begin(&idle->seqcount);
idle_count = ACCESS_ONCE(idle->idle_count); idle_count = ACCESS_ONCE(idle->idle_count);
if (ACCESS_ONCE(idle->clock_idle_enter)) if (ACCESS_ONCE(idle->clock_idle_enter))
idle_count++; idle_count++;
} while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); } while (read_seqcount_retry(&idle->seqcount, seq));
return sprintf(buf, "%llu\n", idle_count); return sprintf(buf, "%llu\n", idle_count);
} }
DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL); DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL);
@ -72,15 +70,15 @@ static ssize_t show_idle_time(struct device *dev,
{ {
struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id);
unsigned long long now, idle_time, idle_enter, idle_exit; unsigned long long now, idle_time, idle_enter, idle_exit;
unsigned int sequence; unsigned int seq;
do { do {
now = get_tod_clock(); now = get_tod_clock();
sequence = ACCESS_ONCE(idle->sequence); seq = read_seqcount_begin(&idle->seqcount);
idle_time = ACCESS_ONCE(idle->idle_time); idle_time = ACCESS_ONCE(idle->idle_time);
idle_enter = ACCESS_ONCE(idle->clock_idle_enter); idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
idle_exit = ACCESS_ONCE(idle->clock_idle_exit); idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
} while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); } while (read_seqcount_retry(&idle->seqcount, seq));
idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0; idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
return sprintf(buf, "%llu\n", idle_time >> 12); return sprintf(buf, "%llu\n", idle_time >> 12);
} }
@ -90,14 +88,14 @@ cputime64_t arch_cpu_idle_time(int cpu)
{ {
struct s390_idle_data *idle = &per_cpu(s390_idle, cpu); struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
unsigned long long now, idle_enter, idle_exit; unsigned long long now, idle_enter, idle_exit;
unsigned int sequence; unsigned int seq;
do { do {
now = get_tod_clock(); now = get_tod_clock();
sequence = ACCESS_ONCE(idle->sequence); seq = read_seqcount_begin(&idle->seqcount);
idle_enter = ACCESS_ONCE(idle->clock_idle_enter); idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
idle_exit = ACCESS_ONCE(idle->clock_idle_exit); idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
} while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence)); } while (read_seqcount_retry(&idle->seqcount, seq));
return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0; return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0;
} }