Re: [PATCH v4 4/6] perf arm-spe: Assign kernel time to synthesized event
From: James Clark <hidden>
Date: 2021-04-15 14:46:42
Also in:
lkml
On 12/04/2021 12:10, Leo Yan wrote:
quoted hunk ↗ jump to hunk
In current code, it assigns the arch timer counter to the synthesized samples Arm SPE trace, thus the samples don't contain the kernel time but only contain the raw counter value. To fix the issue, this patch converts the timer counter to kernel time and assigns it to sample timestamp. Signed-off-by: Leo Yan <redacted> --- tools/perf/util/arm-spe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)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.
sample->ip = record->from_ip; sample->cpumode = arm_spe_cpumode(spe, sample->ip);
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