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

James Clark
2025-09-09T17:17:30Z

On 09/09/2025 10:51 am, James Clark wrote:
>
>
> 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
>

Forgot to mention that everything is available on the FVP model, but
unless the tests are specifically written to run there, they're too
slow. The BRBE branch stack test has been, but SPE and Coresight tests
haven't. So not very useful either unfortunately.

>>> 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>
>>>
>