From: Mel Gorman <mel@csn.ul.ie>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@osdl.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/8] Avoiding fragmentation with subzone groupings v25
Date: Fri, 8 Sep 2006 10:24:59 +0100 (IST) [thread overview]
Message-ID: <Pine.LNX.4.64.0609081020490.7094@skynet.skynet.ie> (raw)
In-Reply-To: <1157704232.17799.48.camel@lappy>
On Fri, 8 Sep 2006, Peter Zijlstra wrote:
> On Thu, 2006-09-07 at 17:58 -0700, Andrew Morton wrote:
>> On Thu, 7 Sep 2006 20:03:42 +0100 (IST)
>> Mel Gorman <mel@csn.ul.ie> wrote:
>>
>>> When a page is allocated, the page-flags
>>> are updated with a value indicating it's type of reclaimability so that it
>>> is placed on the correct list on free.
>>
>> We're getting awful tight on page-flags.
>>
>> Would it be possible to avoid adding the flag? Say, have a per-zone bitmap
>> of size (zone->present_pages/(1<<MAX_ORDER)) bits, then do a lookup in
>> there to work out whether a particular page is within a MAX_ORDER clump of
>> easy-reclaimable pages?
>
> That would not actually work, the fallback allocation path can move
> blocks smaller than MAX_ORDER to another recaim type.
>
Believe it or not, it may be desirably to have a whole block represented
by one or two bits. If a fallback allocation occurs and I move blocks
between lists, I want pages that free later to be freed to the new list as
well. Currently that doesn't happen because the flags are set per-page but
it used to happen in an early version of anti-frag.
> But yeah, page flags are getting right, perhaps Rafael can use his
> recently introduced bitmaps to rid us of the swsusp flags?
>
>
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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next prev parent reply other threads:[~2006-09-08 9:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-07 19:03 [PATCH 0/8] Avoiding fragmentation with subzone groupings v25 Mel Gorman
2006-09-07 19:04 ` [PATCH 1/8] Add __GFP_EASYRCLM flag and update callers Mel Gorman
2006-09-07 19:04 ` [PATCH 2/8] Split the free lists into kernel and user parts Mel Gorman
2006-09-08 7:54 ` Peter Zijlstra
2006-09-08 9:20 ` Mel Gorman
2006-09-07 19:04 ` [PATCH 3/8] Split the per-cpu " Mel Gorman
2006-09-07 19:05 ` [PATCH 4/8] Add a configure option for anti-fragmentation Mel Gorman
2006-09-07 19:05 ` [PATCH 5/8] Drain per-cpu lists when high-order allocations fail Mel Gorman
2006-09-07 19:05 ` [PATCH 6/8] Move free pages between lists on steal Mel Gorman
2006-09-07 19:06 ` [PATCH 7/8] Introduce the RCLM_KERN allocation type Mel Gorman
2006-09-07 19:06 ` [PATCH 8/8] [DEBUG] Add statistics Mel Gorman
2006-09-08 0:58 ` [PATCH 0/8] Avoiding fragmentation with subzone groupings v25 Andrew Morton
2006-09-08 8:30 ` Peter Zijlstra
2006-09-08 9:24 ` Mel Gorman [this message]
2006-09-08 8:36 ` Mel Gorman
2006-09-08 13:06 ` Peter Zijlstra
2006-09-08 13:16 ` Mel Gorman
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