Messages in this thread | | | Date | Tue, 14 Nov 2017 11:28:02 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 4/4] ARCv2: entry: Reduce perf intr return path |
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On Tue, Nov 07, 2017 at 02:13:04PM -0800, Vineet Gupta wrote: > In the more likely case of returning to kernel from perf interrupt, do a > fast path returning w/o bothering about CONFIG_PREEMPT etc
I think this needs more explaining and certainly also deserves a code comment.
Is the argument something along these lines?
Assumes the interrupt will never set TIF_NEED_RESCHED; therefore no preemption is ever required on return from the interrupt.
What do you (on ARC) do about irq_work ?
> +ENTRY(handle_interrupt_pct) > + > + INTERRUPT_PROLOGUE irq > + > + IRQ_DISABLE > + > + lr r0, [ICAUSE] > + > + bl.d arch_do_IRQ > + mov r1, sp > + > + ld r0, [sp, PT_status32] ; returning to User/Kernel Mode > + btst r0, STATUS_U_BIT > + bnz resume_user_mode_begin > + > + clri > + b .Lisr_ret_fast_path_to_k > + > +END(handle_interrupt_pct)
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