lkml.org 
[lkml]   [2016]   [Jul]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] locking/percpu-rwsem: Introduce bias knob
On 07/14, Peter Zijlstra wrote:
>
> The current percpu-rwsem read side is entirely free of serializing
> instructions at the cost of having a synchronize_sched() in the write
> path.
>
> The latency of the synchronize_sched() is too high for some users
> (cgroups), so provide a __percpu_init_rwsem(.bias) argument to forgot
> this synchronize_sched() at the cost of forcing all readers into the
> slow path, which has serializing instructions.

Oh well... I personally do not think this is what we want... Can't
we just add the stupid rcu_sync_enter() into cgroup_init() at least
for now? Yes, this means the unnecessary .sync() at boot time, but
it will go away after cleanups I am going to send.

Because, again, we will probably want to change this bias dynamically.

Oleg.

\
 
 \ /
  Last update: 2016-07-14 21:21    [W:0.178 / U:0.464 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site