linux-kernel - Re: [RFC][PATCH] page reclaim throttle take2

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Message-Id: <20080227095005.4058e109.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 27 Feb 2008 09:50:05 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Balbir Singh <balbir@...ux.vnet.ibm.com>,
	Rik van Riel <riel@...hat.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Nick Piggin <npiggin@...e.de>
Subject: Re: [RFC][PATCH] page reclaim throttle take2

On Tue, 26 Feb 2008 22:18:38 +0100
Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote:

> > +out:
> > +	atomic_dec(&zone->nr_reclaimers);
> > +	wake_up_all(&zone->reclaim_throttle_waitq);
> > +
> > +	return ret;
> > +}
> 
> Would it be possible - and worthwhile - to make this FIFO fair?
> 
I think it doesn't make sense for fairness.

IMHO, this functionality is an unfair one in nature. While someone is
reclaiming pages, other processes can get a newly reclaimed page without
calling try_to_free_page.

For high-priority processes, 

1. avoiding diving into try_to_free_pages if it's congested.
2. just waiting for that someone relcaim pages and grab it ASAP

maybe good for quick work. 

Thanks,
-Kame

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