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Commit 7c2ff389 authored by Ingo Molnar's avatar Ingo Molnar Committed by Jens Axboe
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blktrace: use cpu_clock() instead of sched_clock() 



use cpu_clock() instead of sched_clock(). (the latter is not a proper
clock-source)

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 4d5d8e9d

block/blktrace.c

+10 −10
Original line number Diff line number Diff line
@@ -41,7 +41,7 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action, 
		const int cpu = smp_processor_id();



		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

		t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);

		t->time = cpu_clock(cpu) - per_cpu(blk_trace_cpu_offset, cpu);

		t->device = bt->dev;

		t->action = action;

		t->pid = pid;
@@ -159,7 +159,7 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, 


		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;

		t->sequence = ++(*sequence);

		t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);

		t->time = cpu_clock(cpu) - per_cpu(blk_trace_cpu_offset, cpu);

		t->sector = sector;

		t->bytes = bytes;

		t->action = what;
@@ -488,17 +488,17 @@ void blk_trace_shutdown(struct request_queue *q) 
}



/*

 * Average offset over two calls to sched_clock() with a gettimeofday()

 * Average offset over two calls to cpu_clock() with a gettimeofday()

 * in the middle

 */

static void blk_check_time(unsigned long long *t)

static void blk_check_time(unsigned long long *t, int this_cpu)

{

	unsigned long long a, b;

	struct timeval tv;



	a = sched_clock();

	a = cpu_clock(this_cpu);

	do_gettimeofday(&tv);

	b = sched_clock();

	b = cpu_clock(this_cpu);



	*t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000;

	*t -= (a + b) / 2;
@@ -510,16 +510,16 @@ static void blk_check_time(unsigned long long *t) 
static void blk_trace_check_cpu_time(void *data)

{

	unsigned long long *t;

	int cpu = get_cpu();

	int this_cpu = get_cpu();



	t = &per_cpu(blk_trace_cpu_offset, cpu);

	t = &per_cpu(blk_trace_cpu_offset, this_cpu);



	/*

	 * Just call it twice, hopefully the second call will be cache hot

	 * and a little more precise

	 */

	blk_check_time(t);

	blk_check_time(t);

	blk_check_time(t, this_cpu);

	blk_check_time(t, this_cpu);



	put_cpu();

}