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Commit 8cc42de7 authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarKan Liang <kan.liang@intel.com>
Acked-by: default avatarJiri 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent ebebbf08

tools/perf/builtin-top.c

+9 −0
Original line number Diff line number Diff line
@@ -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");

}



/*