lkml.org 
[lkml]   [2010]   [May]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: commit e9e9250b: sync wakeup bustage when waker is an RT task
From
Date
On Mon, 2010-05-31 at 13:56 +0200, Peter Zijlstra wrote:
> On Sun, 2010-05-16 at 09:21 +0200, Mike Galbraith wrote:
> > sched: RT waker sync wakeup bugfix
> >
> > An RT waker's weight is not on the runqueue, but we try to subrtact it anyway
> > in the sync wakeup case, sending this_load negative. This leads to affine
> > wakeup failure in cases where it should succeed. This was found while testing
> > an PREEMPT_RT kernel with lmbench's lat_udp. In a PREEMPT_RT kernel, softirq
> > threads act as a ~proxy for the !RT buddy. Approximate !PREEMPT_RT sync wakeup
> > behavior by looking at the buddy instead, and subtracting the maximum task weight
> > that will not send this_load negative.
>
>
> Does the below work?

Had to make a dinky adjustment for x86-tip-rt33, but yeah, the horrid
latencies are gone. (hm, skinnier than expected too)

-Mike



\
 
 \ /
  Last update: 2010-05-31 15:59    [W:0.272 / U:0.392 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site