lkml.org 
[lkml]   [2013]   [Jun]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 0/6] ipc/sem.c: performance improvements, FIFO
From
Date
On Sat, 2013-06-15 at 07:27 +0200, Manfred Spraul wrote:

> Assume there is one op (semctl(), whatever) that acquires the global
> lock - and a continuous stream of simple ops.
> - spin_is_locked() returns true due to the semctl().
> - then simple ops will switch to spin_lock(&sma->sem_perm.lock).
> - since the spinlock is acquired, the next operation will get true from
> spin_is_locked().
>
> It will stay that way around - as long as there is at least one op
> waiting for sma->sem_perm.lock.
> With enough cpus, it will stay like this forever.

Yup, pondered that yesterday, scratching my head over how to do better.
Hints highly welcome. Maybe if I figure out how to scratch dual lock
thingy properly for -rt, non-rt will start acting sane too, as that spot
seems to be itchy in both kernels.

-Mike



\
 
 \ /
  Last update: 2013-06-15 08:01    [W:0.096 / U:0.108 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site