lkml.org 
[lkml]   [2017]   [Sep]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH RFC V4 6/6] perf top: check the cost of perf_top__mmap_read
Date
From: Kan Liang <kan.liang@intel.com>

The latency of perf_top__mmap_read should be lower than refresh time.
If not, give some hints to reduce the overhead.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
tools/perf/builtin-top.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 03090d0..b5143c9 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -863,11 +863,20 @@ static void perf_top__mmap_read_idx(struct perf_top *top, int idx)

static void perf_top__mmap_read(struct perf_top *top)
{
+ unsigned long long s, e;
int i;

perf_evlist__toggle_bkw_mmap(top->evlist, BKW_MMAP_DATA_PENDING);
+ s = rdclock();
for (i = 0; i < top->evlist->nr_mmaps; i++)
perf_top__mmap_read_idx(top, i);
+ e = rdclock();
+ if ((e - s) > (unsigned long long)(top->delay_secs * NSEC_PER_SEC)) {
+ ui__warning("Too slow to read ring buffer.\n"
+ "Please try increasing the period (-c) or\n"
+ "decreasing the freq (-F) or\n"
+ "limiting the number of CPUs (-C)\n");
+ }
perf_evlist__toggle_bkw_mmap(top->evlist, BKW_MMAP_EMPTY);
perf_evlist__toggle_bkw_mmap(top->evlist, BKW_MMAP_RUNNING);
}
--
2.5.5
\
 
 \ /
  Last update: 2017-09-29 16:49    [W:0.112 / U:2.832 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site