Re: [PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-09-03 Thread Peter Zijlstra
On Tue, Sep 02, 2014 at 12:41:24AM -0700, Jason Low wrote: > On Mon, 2014-09-01 at 14:55 +0200, Peter Zijlstra wrote: > > But yes, unbounded errors here are a problem, sure relaxing the updates > > makes things go fast, they also make things go skew. > > Okay. In that case, would you like to take

Re: [PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-09-02 Thread Jason Low
On Mon, 2014-09-01 at 14:55 +0200, Peter Zijlstra wrote: > But yes, unbounded errors here are a problem, sure relaxing the updates > makes things go fast, they also make things go skew. Okay. In that case, would you like to take our original patch which avoids unnecessary updates? - Subject:

Re: [PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-09-01 Thread Peter Zijlstra
On Thu, Aug 28, 2014 at 12:46:36PM -0700, Jason Low wrote: > On Wed, 2014-08-27 at 16:32 -0700, Tim Chen wrote: > > If there are multiple non-forced updates, option 1's error seems to > > accumulate and non-bounded as we do not actually update? > > Is this a concern? > > It should be fine. Once

Re: [PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-08-28 Thread Jason Low
On Wed, 2014-08-27 at 16:32 -0700, Tim Chen wrote: > On Wed, 2014-08-27 at 10:34 -0700, Jason Low wrote: > > On Tue, 2014-08-26 at 16:24 -0700, Paul Turner wrote: > > > On Tue, Aug 26, 2014 at 4:11 PM, Jason Low wrote: > > > > Based on perf profiles, the update_cfs_rq_blocked_load function > > >

Re: [PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-08-27 Thread Tim Chen
On Wed, 2014-08-27 at 10:34 -0700, Jason Low wrote: > On Tue, 2014-08-26 at 16:24 -0700, Paul Turner wrote: > > On Tue, Aug 26, 2014 at 4:11 PM, Jason Low wrote: > > > Based on perf profiles, the update_cfs_rq_blocked_load function constantly > > > shows up as taking up a noticeable % of system ru

Re: [PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-08-27 Thread Jason Low
On Tue, 2014-08-26 at 16:24 -0700, Paul Turner wrote: > On Tue, Aug 26, 2014 at 4:11 PM, Jason Low wrote: > > Based on perf profiles, the update_cfs_rq_blocked_load function constantly > > shows up as taking up a noticeable % of system run time. This is especially > > apparent on larger numa syste

Re: [PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-08-26 Thread Paul Turner
On Tue, Aug 26, 2014 at 4:11 PM, Jason Low wrote: > Based on perf profiles, the update_cfs_rq_blocked_load function constantly > shows up as taking up a noticeable % of system run time. This is especially > apparent on larger numa systems. > > Much of the contention is in __update_cfs_rq_tg_load_c

[PATCH v2] sched: Reduce contention in update_cfs_rq_blocked_load

2014-08-26 Thread Jason Low
Based on perf profiles, the update_cfs_rq_blocked_load function constantly shows up as taking up a noticeable % of system run time. This is especially apparent on larger numa systems. Much of the contention is in __update_cfs_rq_tg_load_contrib when we're updating the tg load contribution stats. H