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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
Show stats Download patch file Download diff file Expand all files Collapse all files

3
arch/s390/include/asm/idle.h
View file

@ -9,9 +9,10 @@
#include <linux/types.h>
#include <linux/device.h>
#include <linux/seqlock.h>
struct s390_idle_data {
unsigned int sequence;
seqcount_t seqcount;
unsigned long long idle_count;
unsigned long long idle_time;
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();
/* Account time spent with enabled wait psw loaded as idle time. */
idle->sequence++;
smp_wmb();
write_seqcount_begin(&idle->seqcount);
idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
idle->idle_time += idle_time;
idle->idle_count++;
account_idle_time(idle_time);
smp_wmb();
idle->sequence++;
write_seqcount_end(&idle->seqcount);
}
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);
unsigned long long idle_count;
unsigned int sequence;
unsigned int seq;
do {
sequence = ACCESS_ONCE(idle->sequence);
seq = read_seqcount_begin(&idle->seqcount);
idle_count = ACCESS_ONCE(idle->idle_count);
if (ACCESS_ONCE(idle->clock_idle_enter))
idle_count++;
} while ((sequence & 1) || (ACCESS_ONCE(idle->sequence) != sequence));
} while (read_seqcount_retry(&idle->seqcount, seq));
return sprintf(buf, "%llu\n", idle_count);
}
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);
unsigned long long now, idle_time, idle_enter, idle_exit;
unsigned int sequence;
unsigned int seq;
do {
now = get_tod_clock();
sequence = ACCESS_ONCE(idle->sequence);
seq = read_seqcount_begin(&idle->seqcount);
idle_time = ACCESS_ONCE(idle->idle_time);
idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
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;
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);
unsigned long long now, idle_enter, idle_exit;
unsigned int sequence;
unsigned int seq;
do {
now = get_tod_clock();
sequence = ACCESS_ONCE(idle->sequence);
seq = read_seqcount_begin(&idle->seqcount);
idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
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;
}