lkml.org 
[lkml]   [2023]   [Oct]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [POC][RFC][PATCH v2] sched: Extended Scheduler Time Slice
On Thu, 26 Oct 2023 at 08:36, Mathieu Desnoyers
<mathieu.desnoyers@efficios.com> wrote:
>
> > asm volatile("xchg %b0,%1"
>
> which has an implicit lock prefix (xchg with a memory operand is a
> special-case):

Yeah, this is why we do "percpu_xchg()" - which does not want locked
semantics - as a "cmpxchg" loop.

Steven, check out

arch/x86/include/asm/percpu.h

for a rough implementation of a 'xchg()' without SMP coherency, just
cpu-local one (ie atomic wrt being preempted by the kernel, but not
atomic wrt other CPU's accessing the same variable concurrently)

Linus

\
 
 \ /
  Last update: 2023-10-26 20:58    [W:0.064 / U:0.392 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site