From: Tao Guo <glorioustao@gmail.com>
To: Jeremy Sanders <jeremy@jeremysanders.net>
Cc: linux-raid@vger.kernel.org
Subject: Re: async/X threads and rebuild slowdown
Date: Tue, 16 Mar 2010 21:24:43 +0800 [thread overview]
Message-ID: <318b7ac71003160624m16aad423lddca62c31021b104@mail.gmail.com> (raw)
In-Reply-To: <hnnu9c$tsj$1@dough.gmane.org>
I also meet this problem in several of my machines. If I change back
to kernel 2.6.18, it is
OK, but in 2.6.32 kernel, the performance is really poor.
At last I found a solution, set CONFIG_MULTICORE_RAID456=n when
compiling raid456 module,
then everything goes normal. My machines do have multicore cpu, so it
is weird :<
Maybe there is something wrong with the CONFIG_MULTICORE_RAID456 enabled code?
On Tue, Mar 16, 2010 at 8:41 PM, Jeremy Sanders
<jeremy@jeremysanders.net> wrote:
> Hi - It seems our MD raid rebuild speeds are very slow with the new Fedora
> 2.6.32.9-70 kernel. We're only getting ~13MB/s:
>
> [root@xback2 ~]# cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4]
> md0 : active raid5 sdb1[0] sdj1[10](S) sdk1[9] sdl1[8] sdi1[7] sdh1[6]
> sdg1[5] sdf1[4] sde1[3] sdd1[2] sdc1[1]
> 8788959360 blocks level 5, 32k chunk, algorithm 2 [10/10] [UUUUUUUUUU]
> [=====>...............] resync = 29.3% (286397320/976551040)
> finish=897.2min speed=12819K/sec
>
> The maximum rebuild speed is at the default 200000K/s. The drives are
> connected to a 3ware 9650SE-16ML controller on PCI-Express.
>
> There seem to be hundreds of async/X threads, where X goes up to 129 at
> least. The md0_raid5 process is using at least 80% of the CPU on this dual
> core Athlon 7750 system.
>
> Has anything changed recently in the kernel. I don't remember md0_raid5
> being so processor inefficient, slow at rebuilding or creating hundreds of
> kernel threads.
>
> Are these async/X threads documented anywhere?
>
> Thanks
>
> Jeremy
>
>
>
> --
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--
tao.
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next prev parent reply other threads:[~2010-03-16 13:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-16 12:41 async/X threads and rebuild slowdown Jeremy Sanders
2010-03-16 13:24 ` Tao Guo [this message]
2010-03-16 13:49 ` John Robinson
2010-03-23 21:08 ` Dan Williams
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