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Commit 1ce21804 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Martin Schwidefsky
Browse files

s390/idle: convert open coded idle time seqcount 



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: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 200e7c0f

arch/s390/include/asm/idle.h

+2 −1
Original line number Diff line number Diff line
@@ -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;

arch/s390/kernel/idle.c

+11 −13
Original line number Diff line number Diff line
@@ -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;

}