linux-kernel - Re: [PATCH] mm: disallow direct reclaim page writeback

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Date:	Wed, 14 Apr 2010 15:41:44 +1000
From:	Dave Chinner <david@...morbit.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Chris Mason <chris.mason@...cle.com>, Mel Gorman <mel@....ul.ie>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] mm: disallow direct reclaim page writeback

On Wed, Apr 14, 2010 at 01:59:45PM +0900, KAMEZAWA Hiroyuki wrote:
> On Wed, 14 Apr 2010 11:40:41 +1000
> Dave Chinner <david@...morbit.com> wrote:
> 
> >  50)     3168      64   xfs_vm_writepage+0xab/0x160 [xfs]
> >  51)     3104     384   shrink_page_list+0x65e/0x840
> >  52)     2720     528   shrink_zone+0x63f/0xe10
> 
> A bit OFF TOPIC.
> 
> Could you share disassemble of shrink_zone() ?
> 
> In my environ.
> 00000000000115a0 <shrink_zone>:
>    115a0:       55                      push   %rbp
>    115a1:       48 89 e5                mov    %rsp,%rbp
>    115a4:       41 57                   push   %r15
>    115a6:       41 56                   push   %r14
>    115a8:       41 55                   push   %r13
>    115aa:       41 54                   push   %r12
>    115ac:       53                      push   %rbx
>    115ad:       48 83 ec 78             sub    $0x78,%rsp
>    115b1:       e8 00 00 00 00          callq  115b6 <shrink_zone+0x16>
>    115b6:       48 89 75 80             mov    %rsi,-0x80(%rbp)
> 
> disassemble seems to show 0x78 bytes for stack. And no changes to %rsp
> until retrun.

I see the same. I didn't compile those kernels, though. IIUC,
they were built through the Ubuntu build infrastructure, so there is
something different in terms of compiler, compiler options or config
to what we are both using. Most likely it is the compiler inlining,
though Chris's patches to prevent that didn't seem to change the
stack usage.

I'm trying to get a stack trace from the kernel that has shrink_zone
in it, but I haven't succeeded yet....

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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