Re: cfq misbehaving on 2.6.11-1.14_FC3

From: Andrew Morton
Date: Sat Jun 11 2005 - 04:34:38 EST


<spaminos-ker@xxxxxxxxx> wrote:
>
> Hello, I am running into a very bad problem on one of my production servers.
>
> * the config
> Linux Fedora core 3 latest everything, kernel 2.6.11-1.14_FC3
> AMD Opteron 2 GHz, 1 G RAM, 80 GB Hard drive (IDE, Western Digital)
>
> I have a log processor running in the background, it's using sqlite for storing
> the information it finds in the logs. It takes a few hours to complete a run.
> It's clearly I/O bound (SleepAVG = 98%, according to /proc/pid/status).
> I have to use the cfq scheduler because it's the only scheduler that is fair
> between processes (or should be, keep reading).
>
> * the problem
> Now, after an hour or so of processing, the machine becomes very unresponsive
> when trying to do new disk operations. I say new because existing processes
> that stream data to disk don't seem to suffer so much.

It might be useful to test 2.6.12-rc6-mm1 - it has a substantially
rewritten CFQ implementation.
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