[mythtv-users] pdflush is killing me
Brian Wood
beww at beww.org
Tue Feb 6 00:34:27 UTC 2007
On Feb 5, 2007, at 5:21 PM, Mark Lehrer wrote:
> On Tue, Feb 06, 2007 at 08:20:18AM +1100, Nick Tan wrote:
>
>> According to the kernel documentation, pdflush periodically wakes
>> up and
>> flushes old data to disk. On one of my servers it was set to 5
>> seconds.
>> Here's what I found in the kernel docs:
>
> FYI, here is a cut & paste from another discussion about this; I
> can't wait to get home and try it out:
>
>
>
>> Experience with Ext3 data journaling indicates that dropping
>> expire/writeback
>> can help to smooth out I/O:
>>
>> vm.dirty_expire_centisecs = {300-1000}
>> vm.dirty_writeback_centisecs = {50-100}
>>
>
> The performance limitation which is helped by tuning the VM to push
> dirty pages earlier is in NFS not the underlying filesystem, so this
> technique is useful with XFS too.
>
Hmmm. I'll have to look into that. I'm running an NFS server on a
NSLU2 "slug" and it needs all the help it can get.
Thanks for the info.
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