Commit-ID: 1db6c3a2144eaf0d8aaeecf46df73106834bad75 Gitweb: https://git.kernel.org/tip/1db6c3a2144eaf0d8aaeecf46df73106834bad75 Author: Kan Liang <[email protected]> AuthorDate: Thu, 18 Jan 2018 13:26:32 -0800 Committer: Arnaldo Carvalho de Melo <[email protected]> CommitDate: Tue, 6 Feb 2018 10:11:51 -0300
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 <[email protected]> Acked-by: Jiri Olsa <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Jin Yao <[email protected]> Cc: Namhyung Kim <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Wang Nan <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Arnaldo Carvalho de Melo <[email protected]> --- 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 2b4914f..b7c823b 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"); } /*
