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authorKan Liang <kan.liang@intel.com>2018-01-18 13:26:32 -0800
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-02-15 09:57:06 -0300
commit8cc42de736b617827a4e7664fb8d7a325bc125bc (patch)
treeec87fc8ed11507410243aea4c604e2efa32440bf
parentebebbf082357f86cc84a4d46ce897a5750e41b7a (diff)
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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>
-rw-r--r--tools/perf/builtin-top.c9
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");
}
/*