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

[KAMEZAWA Hiroyuki]

On Wed, 14 Apr 2010 16:19:02 +0900
Minchan Kim <minchan.kim@xxxxxxxxx> wrote:

> On Wed, Apr 14, 2010 at 3:13 PM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
> > On Wed, Apr 14, 2010 at 2:54 PM, KOSAKI Motohiro
> > <kosaki.motohiro@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> wrote:
> >>> >
> >>> > > Â50) Â Â 3168 Â Â Â64 Â xfs_vm_writepage+0xab/0x160 [xfs]
> >>> > > Â51) Â Â 3104 Â Â 384 Â shrink_page_list+0x65e/0x840
> >>> > > Â52) Â Â 2720 Â Â 528 Â shrink_zone+0x63f/0xe10
> >>> >
> >>> > A bit OFF TOPIC.
> >>> >
> >>> > Could you share disassemble of shrink_zone() ?
> >>> >
> >>> > In my environ.
> >>> > 00000000000115a0 <shrink_zone>:
> >>> >  Â115a0:    55           Âpush  %rbp
> >>> >  Â115a1:    48 89 e5        Âmov  Â%rsp,%rbp
> >>> >  Â115a4:    41 57          push  %r15
> >>> >  Â115a6:    41 56          push  %r14
> >>> >  Â115a8:    41 55          push  %r13
> >>> >  Â115aa:    41 54          push  %r12
> >>> >  Â115ac:    53           Âpush  %rbx
> >>> >  Â115ad:    48 83 ec 78       sub  Â$0x78,%rsp
> >>> > Â Â115b1: Â Â Â e8 00 00 00 00 Â Â Â Â Âcallq Â115b6 <shrink_zone+0x16>
> >>> >  Â115b6:    48 89 75 80       mov  Â%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>:
> >  Â1830:    55           Âpush  %ebp
> >  Â1831:    89 e5          mov  Â%esp,%ebp
> >  Â1833:    57           Âpush  %edi
> >  Â1834:    56           Âpush  %esi
> >  Â1835:    53           Âpush  %ebx
> >  Â1836:    81 ec 10 01 00 00    sub  Â$0x110,%esp
> >  Â183c:    89 85 24 ff ff ff    mov  Â%eax,-0xdc(%ebp)
> >  Â1842:    89 95 20 ff ff ff    mov  Â%edx,-0xe0(%ebp)
> >  Â1848:    89 8d 1c ff ff ff    mov  Â%ecx,-0xe4(%ebp)
> >  Â184e:    8b 41 04        Âmov  Â0x4(%ecx)
> >
> > my gcc is following as.
> >
> > barrios@barriostarget:~/mmotm$ 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?
> 

Hmm. about shirnk_zone(), I don't think uninlining functions directly called
by shrink_zone() can be a help.
Total stack size of call-chain will be still big.

Thanks,
-Kame


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