Messages in this thread Patch in this message | | | From | kan.liang@intel ... | Subject | [PATCH V3 12/12] perf top: check the latency of perf_top__mmap_read | Date | Thu, 21 Dec 2017 10:08:54 -0800 |
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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 latency.
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 3c14333..8fb007b 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -877,8 +877,10 @@ static void perf_top__mmap_read(struct perf_top *top) { bool overwrite = top->record_opts.overwrite; struct perf_evlist *evlist = top->evlist; + unsigned long long start, end; int i; + start = rdclock(); if (overwrite) perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_DATA_PENDING); @@ -889,6 +891,13 @@ static void perf_top__mmap_read(struct perf_top *top) perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_EMPTY); perf_evlist__toggle_bkw_mmap(evlist, BKW_MMAP_RUNNING); } + end = rdclock(); + + if ((end - start) > (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"); } /* -- 2.5.5
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