lkml.org 
[lkml]   [2017]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 0/9] Remove spin_unlock_wait()
From
Date
Hi Ingo,

On 07/07/2017 10:31 AM, Ingo Molnar wrote:
>
> There's another, probably just as significant advantage: queued_spin_unlock_wait()
> is 'read-only', while spin_lock()+spin_unlock() dirties the lock cache line. On
> any bigger system this should make a very measurable difference - if
> spin_unlock_wait() is ever used in a performance critical code path.
At least for ipc/sem:
Dirtying the cacheline (in the slow path) allows to remove a smp_mb() in
the hot path.
So for sem_lock(), I either need a primitive that dirties the cacheline
or sem_lock() must continue to use spin_lock()/spin_unlock().

--
Manfred

\
 
 \ /
  Last update: 2017-07-07 19:48    [W:0.146 / U:1.564 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site