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

[Minchan Kim <minchan.kim@gmail.com>]

On Wed, Apr 14, 2010 at 3:13 PM, Minchan Kim <minchan.kim@gmail.com> wrote:
> On Wed, Apr 14, 2010 at 2:54 PM, KOSAKI Motohiro
> <kosaki.motohiro@jp.fujitsu.com> wrote:
>>> 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@fromorbit.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....
>>
>> I also got 0x78 byte stack usage. Umm.. Do we discussed real issue now?
>>
>
> In my case, 0x110 byte in 32 bit machine.
> I think it's possible in 64 bit machine.
>
> 00001830 <shrink_zone>:
>    1830:       55                      push   %ebp
>    1831:       89 e5                   mov    %esp,%ebp
>    1833:       57                      push   %edi
>    1834:       56                      push   %esi
>    1835:       53                      push   %ebx
>    1836:       81 ec 10 01 00 00       sub    $0x110,%esp
>    183c:       89 85 24 ff ff ff       mov    %eax,-0xdc(%ebp)
>    1842:       89 95 20 ff ff ff       mov    %edx,-0xe0(%ebp)
>    1848:       89 8d 1c ff ff ff       mov    %ecx,-0xe4(%ebp)
>    184e:       8b 41 04                mov    0x4(%ecx)
>
> my gcc is following as.
>
> barrios@barriostarget:~/mmotm$ gcc -v
> Using built-in specs.
> Target: i486-linux-gnu
> Configured with: ../src/configure -v --with-pkgversion='Ubuntu
> 4.3.3-5ubuntu4'
> --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs
> --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
> --enable-shared --with-system-zlib --libexecdir=/usr/lib
> --without-included-gettext --enable-threads=posix --enable-nls
> --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3
> --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc
> --enable-mpfr --enable-targets=all --with-tune=generic
> --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu
> --target=i486-linux-gnu
> Thread model: posix
> gcc version 4.3.3 (Ubuntu 4.3.3-5ubuntu4)
>
>
> Is it depends on config?
> I attach my config.

I changed shrink list by noinline_for_stack.
The result is following as.


00001fe0 <shrink_zone>:
    1fe0:       55                      push   %ebp
    1fe1:       89 e5                   mov    %esp,%ebp
    1fe3:       57                      push   %edi
    1fe4:       56                      push   %esi
    1fe5:       53                      push   %ebx
    1fe6:       83 ec 4c                sub    $0x4c,%esp
    1fe9:       89 45 c0                mov    %eax,-0x40(%ebp)
    1fec:       89 55 bc                mov    %edx,-0x44(%ebp)
    1fef:       89 4d b8                mov    %ecx,-0x48(%ebp)

0x110 -> 0x4c.

Should we have to add noinline_for_stack for shrink_list?


-- 
Kind regards,
Minchan Kim

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