Commit-ID: 1db6c3a2144eaf0d8aaeecf46df73106834bad75 Gitweb: https://git.kernel.org/tip/1db6c3a2144eaf0d8aaeecf46df73106834bad75 Author: Kan Liang <kan.li...@intel.com> AuthorDate: Thu, 18 Jan 2018 13:26:32 -0800 Committer: Arnaldo Carvalho de Melo <a...@redhat.com> 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 <kan.li...@intel.com> Acked-by: Jiri Olsa <jo...@kernel.org> Cc: Andi Kleen <a...@linux.intel.com> Cc: Jin Yao <yao....@linux.intel.com> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Wang Nan <wangn...@huawei.com> Link: http://lkml.kernel.org/r/1516310792-208685-18-git-send-email-kan.li...@intel.com Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- 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"); } /*
