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| author | Kan Liang <kan.liang@intel.com> | 2018-01-18 22:26:32 +0100 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-02-15 13:57:06 +0100 |
| commit | 8cc42de736b617827a4e7664fb8d7a325bc125bc (patch) | |
| tree | ec87fc8ed11507410243aea4c604e2efa32440bf /tools/perf/builtin-top.c | |
| parent | perf top: Switch default mode to overwrite mode (diff) | |
| download | linux-8cc42de736b617827a4e7664fb8d7a325bc125bc.tar.xz linux-8cc42de736b617827a4e7664fb8d7a325bc125bc.zip | |
perf top: Check the latency of perf_top__mmap_read()
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>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1516310792-208685-18-git-send-email-kan.liang@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/builtin-top.c')
| -rw-r--r-- | tools/perf/builtin-top.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c index 2b4914f34ed6..b7c823ba8374 100644 --- a/tools/perf/builtin-top.c +++ b/tools/perf/builtin-top.c @@ -889,8 +889,10 @@ 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); @@ -901,6 +903,13 @@ 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"); } /* |