Messages in this thread |  | | Subject | Re: [PATCH 4/4] ARCv2: entry: Reduce perf intr return path | From | Vineet Gupta <> | Date | Tue, 21 Nov 2017 15:26:32 -0800 |
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On 11/17/2017 03:42 PM, Vineet Gupta wrote:
>>>> What do you (on ARC) do about irq_work ? >>> > >> So the reason I'm asking is that some architectures that don't have NMIs >> call irq_work_run() at the very end of their perf-interrupt handler (ARM >> does this for instance). > > But on ARC, we don't call irq_work_run() in perf intr return path and that seem to > imply it is broken - as in latency to service a perf induced preemption.
[snip...]
>>> Although I'm sure it is, can you please explain how irq_work is relevant in >>> the context of this patch. >> >> Since the perf interrupt (in general) cannot call a whole lot of things >> for it needs to assume running from NMI context, it needs to defer >> things to a more regular context. It does this with irq_work.
So given my understanding of this topic, ARC (or any non NMI based perf intr system) is potentially broken without irq_work_run() ?
I can follow up with a patch for ARC, or does this need to addressed for others too - say irq_exit_perf() or some such ?
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