linux-kernel - Re: [PATCH] sched/deadline: No need to check NULL later

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Message-ID: <20160406093036.GQ3448@twins.programming.kicks-ass.net>
Date:	Wed, 6 Apr 2016 11:30:36 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	xlpang@...hat.com
Cc:	linux-kernel@...r.kernel.org, Juri Lelli <juri.lelli@....com>,
	Ingo Molnar <mingo@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH] sched/deadline: No need to check NULL later_mask

On Sat, Apr 02, 2016 at 06:14:28PM +0800, Xunlei Pang wrote:
> Your proposal is very nice!
> 
> At the sched_init() stage we only have one (to be "idle") task and with irq disabled,
> no scheduling will happen, and the cpu_possible_mask was already initiated, so it's
> safe to simply move them there.
> 
> Also, how about rt&deadline sharing a percpu mask? Because only one of them can
> use the mask at a moment, operations are always under some spin_lock_irqsave().
> 
> I made a new patch below, slightly tested by running tens of rt&dl tasks for a while,
> are you fine with it?

Yep, looks fine. Please submit as a proper patch.

Thanks!