lkml.org 
[lkml]   [2011]   [Dec]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [RFC PATCH 0/4] Gang scheduling in CFS
Date
On Mon, 26 Dec 2011 08:44:58 +0530, Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
> On Sun, 25 Dec 2011 12:58:15 +0200, Avi Kivity <avi@redhat.com> wrote:
> > On 12/23/2011 12:36 PM, Ingo Molnar wrote:
> > > * Nikunj A Dadhania <nikunj@linux.vnet.ibm.com> wrote:
> > >
> [...]
> > > >
> > > > I see the main difference between both the reports is:
> > > > native_flush_tlb_others.
> > >
> > > So it would be important to figure out why ebizzy gets into so
> > > many TLB flushes and why gang scheduling makes it go away.
> >
> > The second part is easy - a remote tlb flush involves IPIs to many other
> > vcpus (possible waking them up and scheduling them), then busy-waiting
> > until they acknowledge the flush. Gang scheduling is really good here
> > since it shortens the busy wait, would be even better if we schedule
> > halted vcpus (see the yield_on_hlt module parameter, set to 0).
> I will check this.
>
I am seeing a drop of ~44% when setting yield_on_hlt = 0

Nikunj



\
 
 \ /
  Last update: 2011-12-27 04:21    [W:0.186 / U:0.528 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site