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

[Minchan Kim]

On Wed, Apr 14, 2010 at 6:42 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote:
> 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           Âpush  %ebp
>>   1fe1:    89 e5          mov  Â%esp,%ebp
>>   1fe3:    57           Âpush  %edi
>>   1fe4:    56           Âpush  %esi
>>   1fe5:    53           Âpush  %ebx
>>   1fe6:    83 ec 4c        Âsub  Â$0x4c,%esp
>>   1fe9:    89 45 c0        Âmov  Â%eax,-0x40(%ebp)
>>   1fec:    89 55 bc        Âmov  Â%edx,-0x44(%ebp)
>>   1fef:    89 4d b8        Âmov  Â%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.

Absolutely.
But above 500 byte usage is one of hogger and uninlining is not
critical about reclaim performance. So I think we don't get any lost
than gain.

But I don't get in a hurry. adhoc approach is not good.
I hope when Mel tackles down consumption of stack in reclaim path, he
modifies this part, too.

Thanks.

> Thanks,
> -Kame
>
>
>



-- 
Kind regards,
Minchan Kim
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/