Messages in this thread | | | From | Namhyung Kim <> | Date | Wed, 1 Mar 2023 09:27:44 -0800 | Subject | Re: [PATCH] perf record: Fix "read LOST count failed" msg with sample read |
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Hi Kan,
On Wed, Mar 1, 2023 at 7:04 AM <kan.liang@linux.intel.com> wrote: > > From: Kan Liang <kan.liang@linux.intel.com> > > Hundreds of "read LOST count failed" error messages may be displayed, > when the below command is launched. > > perf record -e '{cpu/mem-loads-aux/,cpu/event=0xcd,umask=0x1/}:S' -a > > According to the commit 89e3106fa25f ("libperf: Handle read format in > perf_evsel__read()"), the PERF_FORMAT_GROUP is only available for the > leader. However, the record__read_lost_samples() goes through every > entry of an evlist, which includes both leader and member. The member > event errors out and triggers the error message. Since there may be > hundreds of CPUs on a server, the message will be printed hundreds of > times, which is very annoying. > > The message itself is correct, but the pr_err is a overkill. Other error > messages in the record__read_lost_samples() are all pr_debug. To make > the output format consistent, change the pr_err("read LOST count > failed\n"); to pr_debug("read LOST count failed\n");. > User can still get the message via -v option. > > Fixes: e3a23261ad06 ("perf record: Read and inject LOST_SAMPLES events") > Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Thanks, Namhyung
> --- > tools/perf/builtin-record.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index 8374117e66f6..be7c0c29d15b 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -1866,7 +1866,7 @@ static void __record__read_lost_samples(struct record *rec, struct evsel *evsel, > int id_hdr_size; > > if (perf_evsel__read(&evsel->core, cpu_idx, thread_idx, &count) < 0) { > - pr_err("read LOST count failed\n"); > + pr_debug("read LOST count failed\n"); > return; > } > > -- > 2.35.1 >
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