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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: Russ Anderson <rja@sgi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Russ Anderson 2010-05-18 17:52:40 -05:00 committed by Arnaldo Carvalho de Melo
parent dfacc4d6c9
commit ef365cefbc
1 changed files with 1 additions and 16 deletions
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17
tools/perf/builtin-record.c
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@ -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++;