Re: kswapd continuously active

[Jan Engelhardt]

On Friday 2010-02-05 14:12, Jens Axboe wrote:
>> >> 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?
>
>barrier=0 is enough. I do wonder why your writeback rate is that slow,
>then. The disk has write back caching enabled?

Yes, that seems to be the case at least. In fact the box is all fluffy 
when nobody runs sync(1), which is what makes it so strange.

sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't 
support DPO or FUA
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