From: NARAYANAN GOPALAKRISHNAN <narayanan.g@samsung.com>
To: Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mel@csn.ul.ie>
Cc: "kamezawa.hiroyu@jp.fujitsu.com" <kamezawa.hiroyu@jp.fujitsu.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"cl@linux-foundation.org" <cl@linux-foundation.org>,
"kosaki.motohiro@jp.fujitsu.com" <kosaki.motohiro@jp.fujitsu.com>,
"stable@kernel.org" <stable@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Subject: Re: Re: Performance degradation seen after using one list for hot/cold pages.
Date: Thu, 09 Jul 2009 04:54:10 +0000 (GMT) [thread overview]
Message-ID: <23853191.513591247115250186.JavaMail.weblogic@epml10> (raw)
> I'll add the rather important text:
>
> Fix a post-2.6.24 performance regression caused by
> 3dfa5721f12c3d5a441448086bee156887daa961 ("page-allocator: preserve PFN
> ordering when __GFP_COLD is set").
>
> This was a pretty major screwup.
>
> This is why changing core MM is so worrisome - there's so much secret and
> subtle history to it, and performance dependencies are unobvious and quite
> indirect and the lag time to discover regressions is long.
>
> Narayanan, are you able to quantify the regression more clearly? All I
> have is "2 MBps lower" which isn't very useful. What is this as a
> percentage, and with what sort of disk controller? Thanks.
It is around 15%. There is no disk controller as our setup is based on Samsung OneNAND
used as a memory mapped device on a OMAP2430 based board.
Narayanan
next reply other threads:[~2009-07-09 4:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-09 4:54 NARAYANAN GOPALAKRISHNAN [this message]
-- strict thread matches above, loose matches on Subject: below --
2009-06-22 10:42 Re: Performance degradation seen after using one list for hot/cold pages NARAYANAN GOPALAKRISHNAN
2009-06-22 11:09 ` Mel Gorman
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