Messages in this thread | | | Date | Tue, 16 Nov 2004 23:00:41 -0800 (PST) | From | Brad Fitzpatrick <> | Subject | Re: 2.6.9: unkillable processes during heavy IO |
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Nathan,
On Wed, 17 Nov 2004, Nathan Scott wrote:
> > > On Sun, 14 Nov 2004, Brad Fitzpatrick wrote: > > > > > > > We have two database servers which freeze up during heavy IO load. The > > Brad, could you send me details on how you've setup mysqld > and how to generate a load similar to yours, so that I can > reproduce the hang locally?
The MySQL people made a tool to reproduce MySQL-like load for the specific purpose of not putting you through the database setup pain:
http://sysbench.sourceforge.net/
To simulate our InnoDB:
-- use the tool to do "seqwr" and write out a 50GB file or so
-- use the tool to make another file, about 30GB.
-- use the tool to do "rndrw" to do random I/O over that 50 GB file, with the O_DIRECT flag on, with a bunch of threads doing 16k reads/writes.
-- use the tool to do random IO w/o O_DIRECT on the smaller file at the same time as the O_DIRECT run, also with a number of threads, doing smaller reads/writes.
This is happening on a machine with LVM2, as well as directly on /dev/sdb2 (an IBM ServeRAID), so device-mapper shouldn't be an issue one way or another.
The filesystem size is 270 GB on one machine (on /dev/sdb2) and 120 GB on LVM2.
> > > > The hardware/software stack is: > > > > > > > > - Dual Opteron 246, SMP kernel, w/ NUMA > > > > - 9 GB of memory (4GB in one zone, 5GB in the other) > > > > - MySQL, running mostly InnoDB, but some MyISAM > > ( I don't even know what those two things are, so you can > probably guess at the level of assistance I'll need here. :)
Well, sysbench should help you find the problem.
Let me know if I can help more. Thanks for looking into this.
- Brad
> > thanks! > > -- > Nathan > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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