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From: Wu Fengguang <fengguang.wu@intel.com>
To: Stefan Priebe <s.priebe@profihost.ag>
Cc: 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 11:26:02 +0800	[thread overview]
Message-ID: <20110826032601.GA26282@localhost> (raw)
In-Reply-To: <D299D0AE-2F3C-42E2-9723-A3D7C0108C40@profihost.ag>

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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  reply	other threads:[~2011-08-26  3:26 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 ` slow performance on disk/network i/o full speed after drop_caches 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 [this message]
2011-08-26  3:30                   ` Zhu Yanhai
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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