From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Paul Turner <pjt@google.com>
Cc: linux-kernel@vger.kernel.org,
Bharata B Rao <bharata@linux.vnet.ibm.com>,
Dhaval Giani <dhaval@linux.vnet.ibm.com>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
Gautham R Shenoy <ego@in.ibm.com>,
Srivatsa Vaddagiri <vatsa@in.ibm.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Ingo Molnar <mingo@elte.hu>, Pavel Emelyanov <xemul@openvz.org>,
Herbert Poetzl <herbert@13thfloor.at>,
Avi Kivity <avi@redhat.com>, Chris Friesen <cfriesen@nortel.com>,
Nikhil Rao <ncrao@google.com>
Subject: Re: [CFS Bandwidth Control v4 5/7] sched: add exports tracking cfs bandwidth control statistics
Date: Fri, 25 Feb 2011 09:54:24 +0100 [thread overview]
Message-ID: <1298624064.2428.1311.camel@twins> (raw)
In-Reply-To: <AANLkTinqp_gfhoLGe0_ShbahzHBLeMZoho46_aMAe17k@mail.gmail.com>
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.
next prev parent reply other threads:[~2011-02-25 8:55 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-16 3:18 [CFS Bandwidth Control v4 0/7] Introduction Paul Turner
2011-02-16 3:18 ` [CFS Bandwidth Control v4 1/7] sched: introduce primitives to account for CFS bandwidth tracking Paul Turner
2011-02-16 16:52 ` Balbir Singh
2011-02-17 2:54 ` Bharata B Rao
2011-02-23 13:32 ` Peter Zijlstra
2011-02-25 3:11 ` Paul Turner
2011-02-25 20:53 ` Paul Turner
2011-02-16 3:18 ` [CFS Bandwidth Control v4 2/7] sched: accumulate per-cfs_rq cpu usage Paul Turner
2011-02-16 17:45 ` Balbir Singh
2011-02-23 13:32 ` Peter Zijlstra
2011-02-25 3:33 ` Paul Turner
2011-02-25 12:31 ` Peter Zijlstra
2011-02-16 3:18 ` [CFS Bandwidth Control v4 3/7] sched: throttle cfs_rq entities which exceed their local quota Paul Turner
2011-02-18 6:52 ` Balbir Singh
2011-02-23 13:32 ` Peter Zijlstra
2011-02-24 5:21 ` Bharata B Rao
2011-02-24 11:05 ` Peter Zijlstra
2011-02-24 15:45 ` Bharata B Rao
2011-02-24 15:52 ` Peter Zijlstra
2011-02-24 16:39 ` Bharata B Rao
2011-02-24 17:20 ` Peter Zijlstra
2011-02-25 3:59 ` Paul Turner
2011-02-25 3:41 ` Paul Turner
2011-02-25 3:10 ` Paul Turner
2011-02-25 13:58 ` Bharata B Rao
2011-02-25 20:51 ` Paul Turner
2011-02-28 3:50 ` Bharata B Rao
2011-02-28 6:38 ` Paul Turner
2011-02-28 13:48 ` Peter Zijlstra
2011-03-01 8:31 ` Paul Turner
2011-03-02 7:23 ` Bharata B Rao
2011-03-02 8:05 ` Paul Turner
2011-02-16 3:18 ` [CFS Bandwidth Control v4 4/7] sched: unthrottle cfs_rq(s) who ran out of quota at period refresh Paul Turner
2011-02-18 7:19 ` Balbir Singh
2011-02-18 8:10 ` Bharata B Rao
2011-02-23 12:23 ` Peter Zijlstra
2011-02-23 13:32 ` Peter Zijlstra
2011-02-24 7:04 ` Bharata B Rao
2011-02-24 11:14 ` Peter Zijlstra
2011-02-26 0:02 ` Paul Turner
2011-02-16 3:18 ` [CFS Bandwidth Control v4 5/7] sched: add exports tracking cfs bandwidth control statistics Paul Turner
2011-02-22 3:14 ` Balbir Singh
2011-02-22 4:13 ` Bharata B Rao
2011-02-22 4:40 ` Balbir Singh
2011-02-23 8:03 ` Paul Turner
2011-02-23 10:13 ` Balbir Singh
2011-02-23 13:32 ` Peter Zijlstra
2011-02-25 3:26 ` Paul Turner
2011-02-25 8:54 ` Peter Zijlstra [this message]
2011-02-16 3:18 ` [CFS Bandwidth Control v4 6/7] sched: hierarchical task accounting for SCHED_OTHER Paul Turner
2011-02-22 3:17 ` Balbir Singh
2011-02-23 8:05 ` Paul Turner
2011-02-23 2:02 ` Hidetoshi Seto
2011-02-23 2:20 ` Paul Turner
2011-02-23 2:43 ` Balbir Singh
2011-02-23 13:32 ` Peter Zijlstra
2011-02-25 3:25 ` Paul Turner
2011-02-25 12:17 ` Peter Zijlstra
2011-02-16 3:18 ` [CFS Bandwidth Control v4 7/7] sched: add documentation for bandwidth control Paul Turner
2011-02-21 2:47 ` [CFS Bandwidth Control v4 0/7] Introduction Xiao Guangrong
2011-02-22 10:28 ` Bharata B Rao
2011-02-23 7:42 ` Paul Turner
2011-02-23 7:51 ` Balbir Singh
2011-02-23 7:56 ` Paul Turner
2011-02-23 8:31 ` Bharata B Rao
[not found] ` <20110224161111.7d83a884@jacob-laptop>
2011-02-25 10:03 ` Paul Turner
2011-02-25 13:06 ` jacob pan
2011-03-08 3:57 ` Balbir Singh
2011-03-08 18:18 ` Jacob Pan
2011-03-09 10:12 ` Paul Turner
2011-03-09 21:57 ` jacob pan
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