lkml.org 
[lkml]   [2014]   [Aug]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v5 tip/core/rcu 15/16] rcu: Make RCU-tasks wait for idle tasks
On Mon, Aug 11, 2014 at 03:49:04PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
>
> Because idle-task code may need to be patched, RCU-tasks need to wait
> for idle tasks to schedule. This commit therefore detects this case
> via context switch. Block CPU hotplug during this time to avoid sending
> IPIs to offline CPUs.
>
> Note that checking for changes in the dyntick-idle counters is tempting,
> but wrong. The reason that it is wrong is that a interrupt or NMI can
> increment these counters without necessarily allowing the idle tasks to
> make any forward progress.

I'm going to NAK this.. with that rcu_idle patch I send there's
typically only a single idle function thats out of bounds and if its
more it can be made that with a bit of tlc to the cpuidle driver in
question.

This needs _FAR_ more justification than a maybe and a want.
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2014-08-13 10:41    [W:0.184 / U:1.104 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site