Re: [Patch v5 16/19] perf/x86: Activate back-to-back NMI detection for arch-PEBS induced NMIs

[Mi, Dapeng]

On 12/8/2025 4:50 PM, Peter Zijlstra wrote:
> On Mon, Dec 08, 2025 at 02:46:44PM +0800, Mi, Dapeng wrote:
>
>> This change only take effects for arch-PEBS. For the legacy PEBS, the
>> "handled" would still be added 1 unconditionally even the *_drain_pebs()
>> helpers always return 0.
>>
>>     /*
>>      * PEBS overflow sets bit 62 in the global status register
>>      */
>>     if (__test_and_clear_bit(GLOBAL_STATUS_BUFFER_OVF_BIT, (unsigned long
>> *)&status)) {
>>         u64 pebs_enabled = cpuc->pebs_enabled;
>>
>>         handled++;
>>         x86_pmu_handle_guest_pebs(regs, &data);
>>         static_call(x86_pmu_drain_pebs)(regs, &data);
>>
> Oh gawd. Please don't do that. If you change the calling convention of
> that function, please have it be used consistently.

Sure. I would do same change for legacy PEBS and make the behavior consistent. 


>