linux-kernel - Re: [RFC] sched: implement the exclusive wait queue as a LIFO queue

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Date:	Wed, 28 Apr 2010 16:15:45 +0800
From:	Yong Zhang <yong.zhang@...driver.com>
To:	Changli Gao <xiaosuo@...il.com>
Cc:	Xiaotian Feng <xtfeng@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Davide Libenzi <davidel@...ilserver.org>,
	Roland Dreier <rolandd@...co.com>,
	Stefan Richter <stefanr@...6.in-berlin.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <dada1@...mosbay.com>,
	Christoph Lameter <cl@...ux.com>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	David Howells <dhowells@...hat.com>,
	Takashi Iwai <tiwai@...e.de>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC] sched: implement the exclusive wait queue as a LIFO queue

On Wed, Apr 28, 2010 at 03:52:01PM +0800, Changli Gao wrote:
> On Wed, Apr 28, 2010 at 3:47 PM, Xiaotian Feng <xtfeng@...il.com> wrote:
> > On Wed, Apr 28, 2010 at 1:03 PM, Changli Gao <xiaosuo@...il.com> wrote:
> >> implement the exclusive wait queue as a LIFO queue
> >>
> >> If the exclusive wait queue is also a LIFO queue as the normal wait queue, the
> >> process who goes to sleep recently, will be woke up first. As its memory is
> >> more likely in cache, we will get better performance. And when there are many
> >> processes waiting on a exclusive wait queue, some of them may not be woke up,
> >> if the others can handle the workload, and it will reduce the load of
> >> the scheduler.
> >>
> >
> > Starve some processes for performance?
> >
> 
> Starve? Oh, No. If we don't need these processes, and we can do better

What do you mean "we don't need these processes"?

> without them, why we wake them up?

So some processs(at the tail of exclusive list)will be treated abnormally
and it will sleep for a long time, is this reasonable?

> 
> 
> -- 
> Regards，
> Changli Gao(xiaosuo@...il.com)
> --
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