lkml.org 
[lkml]   [2010]   [May]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Make sure timers have migrated before killing migration_thread
On Mon, May 24, 2010 at 03:28:45PM +0200, Peter Zijlstra wrote:
> On Mon, 2010-05-24 at 15:29 +0530, Amit K. Arora wrote:
> > since _cpu_up() and _cpu_down() can never run in
> > parallel, because of cpu_add_remove_lock.
>
> Ah indeed. I guess your initial patch works then.

One thing I found surprising was that a cpu's rt-bandwidth renewal could be
dependant on another cpu's (rt-bandwidth) timer firing ontime. In this case, we
had migration/23 pulled over to CPU0 and we hung later waiting for migration/23
to exit. migration/23 was not exiting because it could not run on CPU0 (as
CPU0's rt-bandwidth had expired). This situation remained forever. I would have
expected CPU0's bandwidth to have been renewed independent of some timer on
CPU23 to fire - maybe I am missing something not obvious in the code?

- vatsa


\
 
 \ /
  Last update: 2010-05-24 17:19    [W:0.129 / U:0.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site