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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>
This commit is contained in:
Kan Liang 2018-01-18 13:26:32 -08:00 committed by Arnaldo Carvalho de Melo
parent ebebbf0823
commit 8cc42de736
1 changed files with 9 additions and 0 deletions
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9
tools/perf/builtin-top.c
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@ -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");
}
/*