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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