Message-ID: <1436771221.6576.60.camel@gmail.com>
Subject: Re: [PATCH v2] sched: let __sched_period() use rq's nr_running
From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Byungchul Park <byungchul.park@lge.com>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>, mingo@kernel.org,
        peterz@infradead.org, linux-kernel@vger.kernel.org
Date: Mon, 13 Jul 2015 09:07:01 +0200
In-Reply-To: <20150713005639.GH31287@byungchulpark-X58A-UD3R>
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	 <20150710133107.GC8668@e105550-lin.cambridge.arm.com>
	 <20150713005639.GH31287@byungchulpark-X58A-UD3R>
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On Mon, 2015-07-13 at 09:56 +0900, Byungchul Park wrote:

> and i agree with that it makes latency increase for non-grouped tasks.

It's not only a latency hit for the root group, it's across the board.

I suspect an overloaded group foo/bar/baz would prefer small slices over
a large wait as well. I certainly wouldn't want my root group taking the
potentially huge hits that come with stretching period to accommodate an
arbitrarily overloaded /foo/bar/baz.

	-Mike

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