lkml.org 
[lkml]   [2011]   [Feb]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [CFS Bandwidth Control v4 5/7] sched: add exports tracking cfs bandwidth control statistics
From
Date
On Thu, 2011-02-24 at 19:26 -0800, Paul Turner wrote:
> On Wed, Feb 23, 2011 at 5:32 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> > On Tue, 2011-02-15 at 19:18 -0800, Paul Turner wrote:
> >> + raw_spin_lock(&cfs_b->lock);
> >> + cfs_b->throttled_time += (rq->clock - cfs_rq->throttled_timestamp);
> >> + raw_spin_unlock(&cfs_b->lock);
> >
> > That seems to put the cost of things on the wrong side. Read is rare,
> > update is frequent, and you made the frequent thing the most expensive
> > one.
>
> Hum.. the trade-off here is non-trivial I think
>
> - This update is only once per-quota period (*if* we throttled within
> that period). This places the frequency in the 10s-100s of ms range.
> - Sampling would probably occur on an order of once a second (assuming
> some enterprise management system that cares about these statistics).

Ugh,. people are really polling state like that? If the event is rare
pushing state is much saner.


\
 
 \ /
  Last update: 2011-02-25 09:57    [W:0.109 / U:0.224 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site