Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [PATCH 0/2] arm64: Allow the rescheduling IPI to bypass irq_enter/exit | Date | Tue, 10 Nov 2020 15:48:58 +0000 |
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On 01/01/70 01:00, Valentin Schneider wrote: > On 10/11/20 13:03, Peter Zijlstra wrote: >> On Mon, Nov 02, 2020 at 10:30:50AM +0000, Valentin Schneider wrote: >> >>> Now, I'd like to pen exactly why we think it's okay to forgo irq_{enter, >>> exit}() for that one IRQ and not any other. >> >> Thomas already said a few words on this, but basically scheduler_ipi() >> is a NOP (*almost*), the IPI has no body. All it does is tickle the >> return-from-interrupt path. So any setup and tear-down done for the >> non-existing body is a waste of time.
Gotcha.
The pedant in me thinks this makes it more of a handler property than an IRQ one, but I don't see a nice way to e.g. have this as a flag passed to __request_percpu_irq() and not have it usable by random modules.
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