Messages in this thread | | | Date | Thu, 29 Apr 2021 23:23:26 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v4 4/6] perf arm-spe: Assign kernel time to synthesized event |
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Hi James,
On Fri, Apr 16, 2021 at 03:51:25PM +0300, James Clark wrote:
[...]
> >>> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c > >>> index 23714cf0380e..c13a89f06ab8 100644 > >>> --- a/tools/perf/util/arm-spe.c > >>> +++ b/tools/perf/util/arm-spe.c > >>> @@ -234,7 +234,7 @@ static void arm_spe_prep_sample(struct arm_spe *spe, > >>> struct arm_spe_record *record = &speq->decoder->record; > >>> > >>> if (!spe->timeless_decoding) > >>> - sample->time = speq->timestamp; > >>> + sample->time = tsc_to_perf_time(record->timestamp, &spe->tc); > >> > >> > >> I noticed that in arm_spe_recording_options() the TIME sample bit is set regardless of any options. > >> I don't know of a way to remove this, and if there isn't, does that mean that all the code in this > >> file that looks at spe->timeless_decoding is untested and has never been hit? > >> > >> Unless there is a way to get a perf file with only the AUXTRACE event and no others? I think that one > >> might have no timestamp set. Otherwise other events will always have timestamps so spe->timeless_decoding > >> is always false. > > > > Good point. To be honest, I never noticed this issue until you > > mentioned this. > > > > We should fix for the "timeless" flow; and it's questionable for the > > function arm_spe_recording_options(), except for setting > > PERF_SAMPLE_TIME, it also hard codes for setting > > PERF_SAMPLE_CPU and PERF_SAMPLE_TID. Might need to carefully go > > through this function. > > > > Yeah, it's not strictly related to your change, which is definitely an improvement. > But maybe we should have a look at the SPE implementation relating to timestamps as a whole.
Just now I sent another patch series "perf arm-spe: Correct recording configurations", which is the following up for the issue you found at here.
After correcting sample flags, and combining with current patch series "perf arm-spe: Enable timestamp", I verified the Arm SPE decoding flows for "timeless" decoding, which can work as expected.
So I think we can move forward for this patch series, for easier review, I have uploaded my testing branch wiht the complete patches [1]. Could you help confirm if this works for you? Thanks!
Leo
[1] https://github.com/Leo-Yan/linux/tree/perf_arm_spe_timestamp_v4_with_correcting_sample_flags
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