From: Zhu Yanhai <zhu.yanhai@gmail.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: Stefan Priebe <s.priebe@profihost.ag>,
Pekka Enberg <penberg@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>, Jens Axboe <jaxboe@fusionio.com>,
Linux Netdev List <netdev@vger.kernel.org>
Subject: Re: slow performance on disk/network i/o full speed after drop_caches
Date: Fri, 26 Aug 2011 11:30:35 +0800 [thread overview]
Message-ID: <CAC8teKXqZktBK7+GbLgHn-2k+zjjf8uieRM_q_V7JK7ePAk9Lg@mail.gmail.com> (raw)
In-Reply-To: <20110826032601.GA26282@localhost>
Fengguang,
Maybe it's because zone_reclaim_mode? We often have received some reports that
scp or something like that is slow with no reason, and mostly it's due
to someone
enabled zone_reclaim_mode by mistake.
Stefan, is your zone_reclaim_mode enabled? try 'cat
/proc/sys/vm/zone_reclaim_mode',
and echo 0 to it to disable.
Thanks,
Zhu Yanhai
2011/8/26 Wu Fengguang <fengguang.wu@intel.com>:
> On Fri, Aug 26, 2011 at 11:13:07AM +0800, Stefan Priebe wrote:
>>
>> >> There is at least a numastat proc file.
>> >
>> > Thanks. This shows that node0 is accessed 10x more than node1.
>>
>> What can i do to prevent this or isn't this normal when a machine mostly idles so processes are mostly processed by cpu0.
>
> Yes, that's normal. However it should explain why it's slow even when
> there are lots of free pages _globally_.
>
>> >
>> >> complete ps output:
>> >> http://pastebin.com/raw.php?i=b948svzN
>> >
>> > In that log, scp happens to be in R state and also no other tasks in D
>> > state. Would you retry in the hope of catching some stucked state?
>> Sadly not as the sysrq trigger has rebootet the machine and it will now run fine for 1 or 2 days.
>
> Oops, sorry! It might be possible to reproduce the issue by manually
> eating all of the memory with sparse file data:
>
> truncate -s 1T 1T
> cp 1T /dev/null
>
>> >
>> >>> echo t> /proc/sysrq-trigger
>> >> sadly i wa sonly able to grab the output in this crazy format:
>> >> http://pastebin.com/raw.php?i=MBXvvyH1
>> >
>> > It's pretty readable dmesg, except that the data is incomplete and
>> > there are nothing valuable in the uploaded portion..
>> That was everything i could grab through netconsole. Is there a better way?
>
> netconsole is enough. The partial output should be due to the reboot...
>
> Thanks,
> Fengguang
>
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next prev parent reply other threads:[~2011-08-26 3:30 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4E5494D4.1050605@profihost.ag>
2011-08-24 6:20 ` Pekka Enberg
2011-08-24 9:01 ` Stefan Priebe - Profihost AG
2011-08-24 9:33 ` Wu Fengguang
2011-08-25 9:00 ` Stefan Priebe - Profihost AG
2011-08-26 2:16 ` Wu Fengguang
2011-08-26 2:54 ` Stefan Priebe - Profihost AG
2011-08-26 3:03 ` Wu Fengguang
2011-08-26 3:13 ` Stefan Priebe
2011-08-26 3:26 ` Wu Fengguang
2011-08-26 3:30 ` Zhu Yanhai [this message]
2011-08-26 6:18 ` Stefan Priebe - Profihost AG
2011-08-31 7:11 ` Stefan Priebe - Profihost AG
2011-09-01 4:14 ` Wu Fengguang
2011-09-01 5:41 ` Stefan Priebe - Profihost AG
2011-09-01 12:57 ` Mel Gorman
2011-08-24 9:32 ` Wu Fengguang
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