Re: [PATCH] mm: disallow direct reclaim page writeback

From: KOSAKI Motohiro
Date: Wed Apr 14 2010 - 01:54:25 EST


> 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@xxxxxxxxxxxxx> 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....

I also got 0x78 byte stack usage. Umm.. Do we discussed real issue now?




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