From: Nick Piggin <npiggin@suse.de>
To: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
epasch@de.ibm.com, SCHILLIG@de.ibm.com,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
christof.schmitt@de.ibm.com, thoss@de.ibm.com, hare@suse.de,
gregkh@novell.com
Subject: Re: Performance regression in scsi sequential throughput (iozone) due to "e084b - page-allocator: preserve PFN ordering when __GFP_COLD is set"
Date: Mon, 15 Feb 2010 17:59:14 +1100 [thread overview]
Message-ID: <20100215065913.GK5723@laptop> (raw)
In-Reply-To: <20100212100519.GA29085@laptop>
On Fri, Feb 12, 2010 at 09:05:19PM +1100, Nick Piggin wrote:
> > This leaves me with two ideas what the real issue could be:
> > 1. either really the 6th parameter as this is the first one that needs to go on stack and that way might open a race and rob gcc a big pile of optimization chances
>
> It must be something to do wih code generation AFAIKS. I'm surprised
> the function isn't inlined, giving exactly the same result regardless
> of the patch.
>
> Unlikely to be a correctness issue with code generation, but I'm
> really surprised that a small difference in performance could have
> such a big (and apparently repeatable) effect on behaviour like this.
>
> What's the assembly look like?
Oh, and what happens if you always_inline it? I would have thought
gcc should be able to generate the same code in both cases -- unless
I'm really missing something and there is a functional change in
there?
next prev parent reply other threads:[~2010-02-15 6:59 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-07 14:39 Performance regression in scsi sequential throughput (iozone) due to "e084b - page-allocator: preserve PFN ordering when __GFP_COLD is set" Christian Ehrhardt
2009-12-07 15:09 ` Mel Gorman
2009-12-08 17:59 ` Christian Ehrhardt
2009-12-10 14:36 ` Christian Ehrhardt
2009-12-11 11:20 ` Mel Gorman
2009-12-11 14:47 ` Christian Ehrhardt
2009-12-18 13:38 ` Christian Ehrhardt
2009-12-18 17:42 ` Mel Gorman
2010-01-14 12:30 ` Christian Ehrhardt
2010-01-19 11:33 ` Mel Gorman
2010-02-05 15:51 ` Christian Ehrhardt
2010-02-05 17:49 ` Mel Gorman
2010-02-08 14:01 ` Christian Ehrhardt
2010-02-08 15:21 ` Mel Gorman
2010-02-08 16:55 ` Mel Gorman
2010-02-09 6:23 ` Christian Ehrhardt
2010-02-09 15:52 ` Christian Ehrhardt
2010-02-09 17:57 ` Mel Gorman
2010-02-11 16:11 ` Christian Ehrhardt
2010-02-12 10:05 ` Nick Piggin
2010-02-15 6:59 ` Nick Piggin [this message]
2010-02-15 15:46 ` Christian Ehrhardt
2010-02-16 11:25 ` Mel Gorman
2010-02-16 16:47 ` Christian Ehrhardt
2010-02-17 9:55 ` Christian Ehrhardt
2010-02-17 10:03 ` Christian Ehrhardt
2010-02-18 11:43 ` Mel Gorman
2010-02-18 16:09 ` Christian Ehrhardt
2010-02-19 11:19 ` Christian Ehrhardt
2010-02-19 15:19 ` Mel Gorman
2010-02-22 15:42 ` Christian Ehrhardt
2010-02-25 15:13 ` Christian Ehrhardt
2010-02-26 11:18 ` Nick Piggin
2010-03-02 6:52 ` Nick Piggin
2010-03-02 10:04 ` Mel Gorman
2010-03-02 10:36 ` Nick Piggin
2010-03-02 11:01 ` Mel Gorman
2010-03-02 11:18 ` Nick Piggin
2010-03-02 11:24 ` Mel Gorman
2010-03-03 6:51 ` Christian Ehrhardt
2010-02-08 15:02 ` Christian Ehrhardt
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