[tip:perf/core] perf record: remove unneeded gettimeofday() call

From: tip-bot for Russ Anderson
Date: Fri May 21 2010 - 04:53:22 EST


Commit-ID: ef365cefbc53d8674a18520a1d4c2e5590127299
Gitweb: http://git.kernel.org/tip/ef365cefbc53d8674a18520a1d4c2e5590127299
Author: Russ Anderson <rja@xxxxxxx>
AuthorDate: Tue, 18 May 2010 17:52:40 -0500
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Thu, 20 May 2010 21:53:58 -0300

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@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
LKML-Reference: <20100518225240.GC25589@xxxxxxx>
Signed-off-by: Russ Anderson <rja@xxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-record.c | 17 +----------------
1 files changed, 1 insertions(+), 16 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 66b8ecd..e672269 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -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++;

--
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