Re: [PATCH 0/4] perf arm-spe: Improve --itrace options

James Clark
2025-09-09T17:15:13Z

On 08/09/2025 10:16 pm, Arnaldo Carvalho de Melo wrote:
> On Mon, Sep 08, 2025 at 01:10:17PM +0100, James Clark wrote:
>> Most people also want all the SPE samples (instructions group), not just
>> the flagged samples that are put into the various memory groups. These
>> should have been shown by default but weren't because the default
>> interval type wasn't supported.
>>
>> Also when looking at this, it appears that the downsampling was behaving
>> in a way that would discard samples from one group but not another.
>> Improve that and the warning messages.
>>
>> I don't want to put fixes tags on these because it's only changing the
>> defaults and the behavior, but I don't think the previous behavior was
>> incorrect necessarily, just copied from tracing techs but not ideal for
>> SPE.
>
> I keep trying to find some hardware to have in my homelab to test these
> series, but till then I depend on people having access to such hardware
> for acks or better, tested-by, so waiting a bit for those to appear.
>
> - Arnaldo
>

Unfortunately I don't have any good homelab suggestions. Radxa Orion O6
are the only not-super-expensive boards that have it, but it's not
currently working due to some ACPI issue. AWS Gravitons also have it,
but you currently need a metal instance so that's expensive too.

Leo should be able to have a look at this one until the hardware
trickles down further.

Thanks
James

>> Signed-off-by: James Clark <james.clark@linaro.org>
>> ---
>> James Clark (4):
>> perf arm-spe: Show instruction sample types by default
>> perf arm-spe: Downsample all sample types equally
>> perf arm-spe: Display --itrace period warnings for all sample types
>> perf docs: Update SPE doc to include default instructions group
>>
>> tools/perf/Documentation/perf-arm-spe.txt | 14 +++++---
>> tools/perf/util/arm-spe.c | 53 ++++++++++++++++---------------
>> 2 files changed, 37 insertions(+), 30 deletions(-)
>> ---
>> base-commit: 75a7b9d29215c5aa813b9620f3c56817918f9f8c
>> change-id: 20250908-james-perf-spe-period-4711a566cba4
>>
>> Best regards,
>> --
>> James Clark <james.clark@linaro.org>
>>