Re: [PATCH] perf topdown: Don't require config1==0 for a slots event

[sashiko-bot@kernel.org]

> arch_is_topdown_slots() requires config1 == 0, so it misidentified
> "cpu/slots,metrics_clear=1/" as not being the slots event, and an
> additional slots event gets inserted, which fails event scheduling
> since the group now needs two fixed counter 3.
> 
>   $ perf stat -e "{cpu/slots,metrics_clear=1/,cpu/topdown-retiring/}" -- sleep 1
>   WARNING: events were regrouped to match PMUs
>        <not counted>      slots
>      <not supported>      cpu/slots,metrics_clear=1/
>        <not counted>      cpu/topdown-retiring/
> 
> Drop the config1 == 0 check from arch_is_topdown_slots(). This is
> safe: config1 has no bearing on the event's identifying config value
> (TOPDOWN_SLOTS, 0x0400).
> 
> The attr.type == PERF_TYPE_RAW check is what actually matters: only the
> core PMU is registered with PERF_TYPE_RAW, and on x86, 0x400 is
> guaranteed to be slots event on core CPU.
> 
> arch_is_topdown_metrics() keeps its own config1 == 0 check, since
> genuine metrics events have no "metrics_clear" and config1 remains 0.
> 
> Add a test verifying that an explicit "slots,metrics_clear=1" event in
> a group does not trigger an extra slots event injection.
> 
> Fixes: 5b546de9cc17 ("perf topdown: Use attribute to see an event is a topdown metic or slots")
> Signed-off-by: Zide Chen <zide.chen@intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260917181016.381994-1-zide.chen@intel.com?part=1