lkml.org 
[lkml]   [2017]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 4/4] ARCv2: entry: Reduce perf intr return path
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)

\
 
 \ /
  Last update: 2017-11-14 11:28    [W:0.088 / U:0.492 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site