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>

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