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From: Rik van Riel <riel@redhat.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Konrad Wilk <konrad.wilk@oracle.com>,
	Seth Jennings <sjenning@linux.vnet.ibm.com>,
	Nitin Gupta <ngupta@vflare.org>,
	Nebojsa Trpkovic <trx.lists@gmail.com>,
	minchan@kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Chris Mason <chris.mason@oracle.com>
Subject: Re: [PATCH] mm: implement WasActive page flag (for improving cleancache)
Date: Thu, 26 Jan 2012 22:33:18 -0500	[thread overview]
Message-ID: <4F221AFE.6070108@redhat.com> (raw)
In-Reply-To: <7198bfb3-1e32-40d3-8601-d88aed7aabd8@default>

On 01/26/2012 09:43 PM, Dan Magenheimer wrote:

> Maybe the Active page bit could be overloaded with some minor
> rewriting?  IOW, perhaps the Active bit could be ignored when
> the page is moved to the inactive LRU?  (Confusing I know, but I am
> just brainstorming...)

The PG_referenced bit is already overloaded.  We keep
the bit set when we move a page from the active to the
inactive list, so a page that was previously active
only needs to be referenced once to become active again.

The LRU bits (PG_lru, PG_active, etc) are needed to
figure out which LRU list the page is on.  I don't
think we can overload those...

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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Konrad Wilk <konrad.wilk@oracle.com>,
	Seth Jennings <sjenning@linux.vnet.ibm.com>,
	Nitin Gupta <ngupta@vflare.org>,
	Nebojsa Trpkovic <trx.lists@gmail.com>,
	minchan@kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Chris Mason <chris.mason@oracle.com>
Subject: Re: [PATCH] mm: implement WasActive page flag (for improving cleancache)
Date: Thu, 26 Jan 2012 22:33:18 -0500	[thread overview]
Message-ID: <4F221AFE.6070108@redhat.com> (raw)
In-Reply-To: <7198bfb3-1e32-40d3-8601-d88aed7aabd8@default>

On 01/26/2012 09:43 PM, Dan Magenheimer wrote:

> Maybe the Active page bit could be overloaded with some minor
> rewriting?  IOW, perhaps the Active bit could be ignored when
> the page is moved to the inactive LRU?  (Confusing I know, but I am
> just brainstorming...)

The PG_referenced bit is already overloaded.  We keep
the bit set when we move a page from the active to the
inactive list, so a page that was previously active
only needs to be referenced once to become active again.

The LRU bits (PG_lru, PG_active, etc) are needed to
figure out which LRU list the page is on.  I don't
think we can overload those...

-- 
All rights reversed

  reply	other threads:[~2012-01-27  3:33 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-25 21:58 [PATCH] mm: implement WasActive page flag (for improving cleancache) Dan Magenheimer
2012-01-25 21:58 ` Dan Magenheimer
2012-01-26 17:28 ` Dave Hansen
2012-01-26 17:28   ` Dave Hansen
2012-01-26 21:28   ` Dan Magenheimer
2012-01-26 21:28     ` Dan Magenheimer
2012-01-27  0:31     ` Andrew Morton
2012-01-27  0:31       ` Andrew Morton
2012-01-27  0:56       ` Dan Magenheimer
2012-01-27  0:56         ` Dan Magenheimer
2012-01-27  1:15         ` Andrew Morton
2012-01-27  1:15           ` Andrew Morton
2012-01-27  2:43           ` Dan Magenheimer
2012-01-27  2:43             ` Dan Magenheimer
2012-01-27  3:33             ` Rik van Riel [this message]
2012-01-27  3:33               ` Rik van Riel
2012-01-27  5:15               ` Dan Magenheimer
2012-01-27  5:15                 ` Dan Magenheimer
2012-01-30  8:57                 ` KAMEZAWA Hiroyuki
2012-01-30  8:57                   ` KAMEZAWA Hiroyuki
2012-01-30 22:03                   ` Dan Magenheimer
2012-01-30 22:03                     ` Dan Magenheimer
2012-01-27 13:43             ` James Bottomley
2012-01-27 13:43               ` James Bottomley
2012-01-27 17:32               ` Dan Magenheimer
2012-01-27 17:32                 ` Dan Magenheimer
2012-01-27 17:54                 ` James Bottomley
2012-01-27 17:54                   ` James Bottomley
2012-01-27 18:46                   ` Dan Magenheimer
2012-01-27 18:46                     ` Dan Magenheimer
2012-01-27 21:49                     ` James Bottomley
2012-01-27 21:49                       ` James Bottomley
2012-01-29  0:50                       ` Rik van Riel
2012-01-29  0:50                         ` Rik van Riel
2012-01-29 22:25                         ` James Bottomley
2012-01-29 22:25                           ` James Bottomley
2012-01-27  3:28         ` Rik van Riel
2012-01-27  3:28           ` Rik van Riel
2012-01-27  5:11           ` Dan Magenheimer
2012-01-27  5:11             ` Dan Magenheimer

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