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Re: [PATCH 0/8] Use memory compaction instead of lumpy reclaim during high-order allocations

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From: Mel Gorman
Subject: Re: [PATCH 0/8] Use memory compaction instead of lumpy reclaim during high-order allocations
Date: Friday, November 19, 2010 - 3:48 am

On Thu, Nov 18, 2010 at 11:49:28AM -0800, Andrew Morton wrote:

At least as long as !CONFIG_COMPACTION exists. That will be a while because
bear in mind CONFIG_COMPACTION is disabled by default (although I believe
some distros are enabling it at least). Maybe we should choose to deprecate
it in 2.6.40 and delete it at the infamous time of 2.6.42? That would give
ample time to iron out any issues that crop up with reclaim/compaction
(what this series has turned into).

Bear in mind that lumpy reclaim is heavily isolated these days. The logic
is almost entirely contained in isolate_lru_pages() in the block starting
with the comment "Attempt to take all pages in the order aligned region
surrounding the tag page". As disruptive as lumpy reclaim is, it's basically
just a linear scanner at the end of the day and there are a few examples of
that in the kernel. If we break it, it'll be obvious.


I'm open to its ultimate deletion but think it's rash to do on day 1 of
reclaim/compaction. I do recognise that I might be entirely on my own with
this opinion though :)

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
--
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Messages in current thread:
[PATCH 0/8] Use memory compaction instead of lumpy reclaim ..., Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 1/8] mm: compaction: Add trace events for memory co ..., Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 2/8] mm: vmscan: Convert lumpy_mode into a bitmask, Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 3/8] mm: vmscan: Reclaim order-0 and use compaction ..., Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 4/8] mm: migration: Allow migration to operate asyn ..., Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 5/8] mm: migration: Cleanup migrate_pages API by ma ..., Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 6/8] mm: compaction: Perform a faster scan in try_t ..., Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 7/8] mm: compaction: Use the LRU to get a hint on w ..., Mel Gorman, (Wed Nov 17, 9:22 am)
[PATCH 8/8] mm: vmscan: Rename lumpy_mode to reclaim_mode, Mel Gorman, (Wed Nov 17, 9:22 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Andrew Morton, (Wed Nov 17, 4:46 pm)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Rik van Riel, (Wed Nov 17, 7:03 pm)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Mel Gorman, (Thu Nov 18, 1:12 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., KAMEZAWA Hiroyuki, (Thu Nov 18, 1:26 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Johannes Weiner, (Thu Nov 18, 1:38 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Mel Gorman, (Thu Nov 18, 1:44 am)
Re: [PATCH 7/8] mm: compaction: Use the LRU to get a hint ..., KAMEZAWA Hiroyuki, (Thu Nov 18, 2:10 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Mel Gorman, (Thu Nov 18, 2:20 am)
Re: [PATCH 7/8] mm: compaction: Use the LRU to get a hint ..., Mel Gorman, (Thu Nov 18, 2:28 am)
Re: [PATCH 3/8] mm: vmscan: Reclaim order-0 and use compac ..., Andrea Arcangeli, (Thu Nov 18, 11:09 am)
Re: [PATCH 4/8] mm: migration: Allow migration to operate ..., Andrea Arcangeli, (Thu Nov 18, 11:21 am)
Re: [PATCH 3/8] mm: vmscan: Reclaim order-0 and use compac ..., Mel Gorman, (Thu Nov 18, 11:30 am)
Re: [PATCH 4/8] mm: migration: Allow migration to operate ..., Mel Gorman, (Thu Nov 18, 11:34 am)
Re: [PATCH 6/8] mm: compaction: Perform a faster scan in t ..., Andrea Arcangeli, (Thu Nov 18, 11:34 am)
Re: [PATCH 7/8] mm: compaction: Use the LRU to get a hint ..., Andrea Arcangeli, (Thu Nov 18, 11:46 am)
Re: [PATCH 6/8] mm: compaction: Perform a faster scan in t ..., Mel Gorman, (Thu Nov 18, 11:50 am)
Re: [PATCH 4/8] mm: migration: Allow migration to operate ..., Andrea Arcangeli, (Thu Nov 18, 12:00 pm)
Re: [PATCH 6/8] mm: compaction: Perform a faster scan in t ..., Andrea Arcangeli, (Thu Nov 18, 12:08 pm)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Andrew Morton, (Thu Nov 18, 12:49 pm)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Mel Gorman, (Fri Nov 19, 3:48 am)
Re: [PATCH 7/8] mm: compaction: Use the LRU to get a hint ..., Mel Gorman, (Fri Nov 19, 4:08 am)
Re: [PATCH 6/8] mm: compaction: Perform a faster scan in t ..., Mel Gorman, (Fri Nov 19, 4:16 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Theodore Tso, (Fri Nov 19, 5:43 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Mel Gorman, (Fri Nov 19, 7:05 am)
Re: [PATCH 0/8] Use memory compaction instead of lumpy rec ..., Ted Ts'o, (Fri Nov 19, 8:45 am)