From: Peter Zijlstra <peterz@infradead.org>
To: Xunlei Pang <pang.xunlei@linaro.org>
Cc: linux-kernel@vger.kernel.org, Juri Lelli <juri.lelli@gmail.com>
Subject: Re: [PATCH 2/5] sched/deadline: Remove cpu_active_mask from cpudl_find()
Date: Tue, 27 Jan 2015 16:04:46 +0100 [thread overview]
Message-ID: <20150127150446.GF21418@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1421642980-10045-2-git-send-email-pang.xunlei@linaro.org>
On Mon, Jan 19, 2015 at 04:49:37AM +0000, Xunlei Pang wrote:
> cpu_active_mask is rarely changeable, so remove this operation
> to gain a little performance.
>
> If there is a change in cpu_active_mask, rq_online_dl() and
> rq_offline_dl() should take care of it normally, so cpudl::
> free_cpus carries enough information for us.
>
> For the rare case(causing a task put onto a dying cpu) which
> rq_offline_dl() can't handle timely, then it can be handled
> through _cpu_down()->...->multi_cpu_stop()->migration_call()
> ->migrate_tasks(), preventing the task from hanging on the
> dead cpu.
Maybe; I'll need to go crawl through the long and twisted history of
active_mask here :/
next prev parent reply other threads:[~2015-01-27 15:04 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-19 4:49 [PATCH 1/5] sched/deadline: Modify cpudl::free_cpus to reflect rd->online Xunlei Pang
2015-01-19 4:49 ` [PATCH 2/5] sched/deadline: Remove cpu_active_mask from cpudl_find() Xunlei Pang
2015-01-27 15:04 ` Peter Zijlstra [this message]
2015-02-04 14:36 ` [tip:sched/core] " tip-bot for Xunlei Pang
2015-01-19 4:49 ` [PATCH 3/5] sched/deadline: Fix wrong cpudl_find() in check_preempt_equal_dl() Xunlei Pang
2015-01-27 12:48 ` Peter Zijlstra
2015-01-27 14:15 ` Peter Zijlstra
2015-01-27 16:47 ` Peter Zijlstra
2015-01-28 15:18 ` Xunlei Pang
2015-01-19 4:49 ` [PATCH 4/5] sched/rt: Consider deadline tasks in cpupri_find() Xunlei Pang
2015-01-27 12:58 ` Peter Zijlstra
2015-01-27 14:18 ` Peter Zijlstra
2015-01-27 23:04 ` Steven Rostedt
2015-01-28 15:21 ` Xunlei Pang
2015-01-19 4:49 ` [PATCH 5/5] sched/rt: Optimize find_lowest_rq() to select a cache hot cpu Xunlei Pang
2015-01-27 14:21 ` Peter Zijlstra
2015-01-27 14:56 ` Steven Rostedt
2015-01-27 16:28 ` Peter Zijlstra
2015-01-29 16:42 ` Xunlei Pang
2015-01-29 17:17 ` Steven Rostedt
2015-01-29 19:23 ` Peter Zijlstra
2015-02-04 13:07 ` Xunlei Pang
2015-01-23 18:09 ` [PATCH 1/5] sched/deadline: Modify cpudl::free_cpus to reflect rd->online Xunlei Pang
2015-02-01 17:53 ` [tip:sched/core] sched/deadline: Modify cpudl:: free_cpus " tip-bot for Xunlei Pang
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