linux-kernel - Re: [PATCH 1/2] perf arm-spe: Add arm_spe

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Date:   Wed, 26 Jan 2022 15:58:20 +0000
From:   Ali Saidi <alisaidi@...zon.com>
To:     <german.gomez@....com>
CC:     <acme@...nel.org>, <alexander.shishkin@...ux.intel.com>,
        <alisaidi@...zon.com>, <andrew.kilroy@....com>,
        <benh@...nel.crashing.org>, <james.clark@....com>,
        <john.garry@...wei.com>, <jolsa@...hat.com>, <leo.yan@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-perf-users@...r.kernel.org>,
        <mark.rutland@....com>, <mathieu.poirier@...aro.org>,
        <mingo@...hat.com>, <namhyung@...nel.org>, <peterz@...radead.org>,
        <will@...nel.org>
Subject: Re: [PATCH 1/2] perf arm-spe: Add arm_spe_record to synthesized

Hi German,
>Hi Ali,
>
>On 25/01/2022 19:20, Ali Saidi wrote:
>> Providing the arm_spe_record as raw data to the synthesized SPE samples
>> allows perf scripts to read and separately process the data in ways
>> existing perf tools don't support and mirrors functionality available
>> for PEBS.
>> Signed-off-by: Ali Saidi <alisaidi@...zon.com>
>> ---
>>  tools/perf/util/arm-spe.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
>> index d2b64e3f588b..a7499cde6fc0 100644
>> --- a/tools/perf/util/arm-spe.c
>> +++ b/tools/perf/util/arm-spe.c
>> @@ -336,6 +336,8 @@ static int arm_spe__synth_mem_sample(struct arm_spe_queue *speq,
>>  	sample.phys_addr = record->phys_addr;
>>  	sample.data_src = data_src;
>>  	sample.weight = record->latency;
>> +	sample.raw_size = sizeof(*record);
>> +	sample.raw_data = record;
>
>Have you tried this with perf-inject? I think it would need the PERF_SAMPLE_RAW bit in the sample_type,

Yes I've tried the following and it worked as expected with the original
perf.data or the perf.data.jitted after perf-inject. 

perf record -e arm_spe_0/jitter=1/ -k 1 java ...
perf  inject -f --jit -i perf.data -o perf.data.jitted
perf script -i perf.data -s t1.py --itrace=i1i

>
>Although I quickly looked over the perf inject code and it looks like it's expecting some type of padding:
>
>  // synthetic-events.c
>  if (type & PERF_SAMPLE_RAW) {
>    result += sizeof(u32);
>    result += sample->raw_size;
>  }
>
>I'm seeing some comments in utils/event.h related to this on the intel events.

Yes i noticed this too,but looking at how the raw data is added to the same
other places like intel-pt.c:1703 the perf_synth__raw*() functions are used to
strip away the 4 bytes bytes before the data is added to the sample. The other
places i can find the padding used is in builtin-script.c but given we have the
--dump-raw-trace option it's not clear to me that it's needed to wrap the
arm_spe_event in another struct with padding like perf_synth_intel_ptwrite?

Thanks,
Ali