From: Ingo Molnar <mingo@elte.hu>
To: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org,
Bharata B Rao <bharata@linux.vnet.ibm.com>,
Dhaval Giani <dhaval.giani@gmail.com>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
Srivatsa Vaddagiri <vatsa@in.ibm.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>,
Pavel Emelyanov <xemul@openvz.org>, Hu Tao <hutao@cn.fujitsu.com>
Subject: Re: [patch 00/17] CFS Bandwidth Control v7.1
Date: Sun, 10 Jul 2011 20:12:05 +0200 [thread overview]
Message-ID: <20110710181205.GA21375@elte.hu> (raw)
In-Reply-To: <CAPM31RLy4hvaRUi5iVeOyEapRtguR5rNUrn+3oGax_Mm3GxqTw@mail.gmail.com>
* Paul Turner <pjt@google.com> wrote:
> Finally introducing jump labels when there are no constrained
> groups claws back a good portion of the remaining time.
>
> Add jump labels:
> cycles instructions
> branches
> ----------------------------------------------------------------------------------------------------
> base 893,486,206 840,904,951 160,076,980
> +unconstrained 900,477,543 (+0.78) 890,310,950 (+5.88)
> 161,037,844 (+0.60)
> +10000000000/1000: 921,436,697 (+3.13) 919,362,792 (+9.33)
> 168,491,279 (+5.26)
> +10000000000/10000: 907,214,638 (+1.54) 894,406,875 (+6.36)
> 165,743,207 (+3.54)
> +10000000000/100000: 918,094,542 (+2.75) 910,211,234 (+8.24)
> 167,841,828 (+4.85)
> +10000000000/1000000: 910,698,725 (+1.93) 885,385,460 (+5.29)
> 166,406,742 (+3.95)
That looks pretty promising!
The +5% instruction count still looks a tad high to me: if there are
about 1000 instructions in this particular contex-switch critical
path then 5% means +50 instructions - a 'disabled' feature sure
should not use that many instructions, right?
Also, i have a testing suggestion, i'd suggest to run:
taskset 1 perf stat ...
to only measure while pinned on a single CPU. This will remove a lot
of cross-CPU noise from the context switching overhead.
This is a valid way to progress because we are interested in the
typical context-switch overhead on a single CPU - we know that
there's no SMP cost when constraining is disabled.
Doing that should bring your measurement noise below the 0.1% range i
suspect. As you are shaving off cycle after cycle i think you'll need
that kind of measurement precision ...
Thanks,
Ingo
next prev parent reply other threads:[~2011-07-10 18:12 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-07 5:30 Paul Turner
2011-07-07 5:30 ` [patch 01/17] sched: (fixlet) dont update shares twice on on_rq parent Paul Turner
2011-07-21 18:28 ` [tip:sched/core] sched: Don't " tip-bot for Paul Turner
2011-07-07 5:30 ` [patch 02/17] sched: hierarchical task accounting for SCHED_OTHER Paul Turner
2011-07-07 5:30 ` [patch 03/17] sched: introduce primitives to account for CFS bandwidth tracking Paul Turner
2011-07-07 13:48 ` Peter Zijlstra
2011-07-07 21:30 ` Paul Turner
2011-07-07 5:30 ` [patch 04/17] sched: validate CFS quota hierarchies Paul Turner
2011-07-07 5:30 ` [patch 05/17] sched: accumulate per-cfs_rq cpu usage and charge against bandwidth Paul Turner
2011-07-07 5:30 ` [patch 06/17] sched: add a timer to handle CFS bandwidth refresh Paul Turner
2011-07-07 5:30 ` [patch 07/17] sched: expire invalid runtime Paul Turner
2011-07-07 5:30 ` [patch 08/17] sched: add support for throttling group entities Paul Turner
2011-07-07 5:30 ` [patch 09/17] sched: add support for unthrottling " Paul Turner
2011-07-07 5:30 ` [patch 10/17] sched: allow for positional tg_tree walks Paul Turner
2011-07-07 5:30 ` [patch 11/17] sched: prevent interactions with throttled entities Paul Turner
2011-07-07 5:30 ` [patch 12/17] sched: prevent buddy " Paul Turner
2011-07-07 5:30 ` [patch 13/17] sched: migrate throttled tasks on HOTPLUG Paul Turner
2011-07-07 5:30 ` [patch 14/17] sched: throttle entities exceeding their allowed bandwidth Paul Turner
2011-07-07 5:30 ` [patch 15/17] sched: add exports tracking cfs bandwidth control statistics Paul Turner
2011-07-07 5:30 ` [patch 16/17] sched: return unused runtime on group dequeue Paul Turner
2011-07-07 5:30 ` [patch 17/17] sched: add documentation for bandwidth control Paul Turner
2011-07-07 11:13 ` [patch 00/17] CFS Bandwidth Control v7.1 Peter Zijlstra
2011-07-11 1:22 ` Hu Tao
2011-07-07 11:23 ` Ingo Molnar
2011-07-07 11:28 ` Peter Zijlstra
2011-07-07 14:38 ` Peter Zijlstra
2011-07-07 14:51 ` Ingo Molnar
2011-07-07 14:54 ` Peter Zijlstra
2011-07-07 14:56 ` Ingo Molnar
2011-07-07 16:23 ` Jason Baron
2011-07-07 17:20 ` Peter Zijlstra
2011-07-07 18:15 ` Jason Baron
2011-07-07 20:36 ` jump_label defaults (was Re: [patch 00/17] CFS Bandwidth Control v7.1) Peter Zijlstra
2011-07-08 9:20 ` Peter Zijlstra
2011-07-08 15:47 ` Jason Baron
2011-07-07 16:52 ` [patch 00/17] CFS Bandwidth Control v7.1 Andi Kleen
2011-07-07 17:08 ` Peter Zijlstra
2011-07-07 17:59 ` Peter Zijlstra
2011-07-07 19:36 ` Jason Baron
2011-07-08 7:45 ` Paul Turner
2011-07-08 7:39 ` Paul Turner
2011-07-08 10:32 ` Peter Zijlstra
2011-07-09 7:34 ` Paul Turner
2011-07-10 18:12 ` Ingo Molnar [this message]
2011-07-07 14:06 ` Peter Zijlstra
2011-07-08 7:35 ` Paul Turner
2011-07-11 1:22 ` Hu Tao
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