Commit ef365cef authored by Russ Anderson's avatar Russ Anderson Committed by Arnaldo Carvalho de Melo
Browse files

perf record: remove unneeded gettimeofday() call 



Perf record repeatedly calls gettimeofday() which adds noise to the performance
measurements.  Since gettimeofday() is only used for the error printf, delete
it.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
LKML-Reference: <20100518225240.GC25589@sgi.com>
Signed-off-by: default avatarRuss Anderson <rja@sgi.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent dfacc4d6

tools/perf/builtin-record.c

+1 −16
Original line number Diff line number Diff line
@@ -65,9 +65,6 @@ static bool multiplex = false; 
static int			multiplex_fd			=     -1;



static long			samples				=      0;

static struct timeval		last_read;

static struct timeval		this_read;



static u64			bytes_written			=      0;



static struct pollfd		*event_array;
@@ -147,8 +144,6 @@ static void mmap_read(struct mmap_data *md) 
	void *buf;

	int diff;



	gettimeofday(&this_read, NULL);



	/*

	 * If we're further behind than half the buffer, there's a chance

	 * the writer will bite our tail and mess up the samples under us.
@@ -159,23 +154,13 @@ static void mmap_read(struct mmap_data *md) 
	 */

	diff = head - old;

	if (diff < 0) {

		struct timeval iv;

		unsigned long msecs;



		timersub(&this_read, &last_read, &iv);

		msecs = iv.tv_sec*1000 + iv.tv_usec/1000;



		fprintf(stderr, "WARNING: failed to keep up with mmap data."

				"  Last read %lu msecs ago.\n", msecs);



		fprintf(stderr, "WARNING: failed to keep up with mmap data\n");

		/*

		 * head points to a known good entry, start there.

		 */

		old = head;

	}



	last_read = this_read;



	if (old != head)

		samples++;

CRA Git | Maintained and supported by SUSTech CRA and CCSE