From: Mel Gorman <mel@csn.ul.ie>
To: Iram Shahzad <iram.shahzad@jp.fujitsu.com>
Cc: linux-mm@kvack.org
Subject: Re: compaction: why depends on HUGETLB_PAGE
Date: Thu, 29 Jul 2010 13:57:25 +0100 [thread overview]
Message-ID: <20100729125725.GA3571@csn.ul.ie> (raw)
In-Reply-To: <D25878F935704D9281E62E0393CAD951@rainbow>
On Thu, Jul 29, 2010 at 10:53:12AM +0900, Iram Shahzad wrote:
> Hi
>
> I have found that memory compaction (CONFIG_COMPACTION)
> is mainlined while looking at 2.6.35-rc5 source code.
> I have a question regarding its dependency on HUGETLB_PAGE.
>
> While trying to use CONFIG_COMPACTION on ARM architecture,
> I found that I cannot enable CONFIG_COMPACTION because
> it depends on CONFIG_HUGETLB_PAGE which is not available
> on ARM.
>
> I disabled the dependency and was able to build it.
> And it looks like working!
>
> My question is: why does it depend on CONFIG_HUGETLB_PAGE?
Because as the Kconfig says "Allows the compaction of memory for the
allocation of huge pages.". Depending on compaction to satisfy other
high-order allocation types is not likely to be a winning strategy.
> Is it wrong to use it on ARM by disabling CONFIG_HUGETLB_PAGE?
>
It depends on why you need compaction. If it's for some device that
requires high-order allocations (particularly if they are atomic), then
it's not likely to work very well in the long term.
--
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:[~2010-07-29 12:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-29 1:53 compaction: why depends on HUGETLB_PAGE Iram Shahzad
2010-07-29 12:57 ` Mel Gorman [this message]
2010-07-30 2:56 ` Iram Shahzad
2010-07-30 9:57 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2010-07-30 16:44 Round Robinjp
2010-07-30 16:49 ` Mel Gorman
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