linux-kernel - Re: kswapd continuously active

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Message-ID: <alpine.LSU.2.01.1002051408280.23211@obet.zrqbmnf.qr>
Date:	Fri, 5 Feb 2010 14:09:01 +0100 (CET)
From:	Jan Engelhardt <jengelh@...ozas.de>
To:	Jens Axboe <jens.axboe@...cle.com>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: kswapd continuously active


On Friday 2010-02-05 14:00, Jens Axboe wrote:
>> >January 25			Feb-05
>> >MemTotal:        8166752 kB	8166752
>> >MemFree:         3243552 kB	3781776
>> >Buffers:          207968 kB	4912
>> >Cached:          2728216 kB	2684400
>> >SwapCached:            0 kB	0
>> >Active:          2203136 kB	495624
>> >Inactive:        2152544 kB	3263136
>> >Active(anon):    1167256 kB	488168
>> >Inactive(anon):   252952 kB	583912
>> >Active(file):    1035880 kB	7456
>> >Inactive(file):  1899592 kB	2679224
>> >Unevictable:           0 kB	0
>> >Mlocked:               0 kB	0
>> >SwapTotal:             0 kB	0
>> >SwapFree:              0 kB	0
>> >Dirty:            141624 kB	2662184
>> >Writeback:             0 kB	..
>> 
>> Today this happened again. So I looked at /proc/meminfo to paste today's
>> values next to those from January. That is when I noticed the "Dirty"
>> value - and thus I ran
>> 
>> 	watch -d -n 1 'grep Dirty /proc/meminfo'
>> 
>> What I see is that the dirty amount - a sync is currently running -
>> only decreases with at most 400 KB/sec, often less than that.
>
>I'm guessing the barriers and commits are what is killing your
>performance. What happens with barrier=0?

The ext4 filesystem is already mounted with barrier=0. If there
is any block-level barriers I also can turn off, what would be
the command?


thanks,
Jan
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