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Re: Much Slower than 7.2?



On Mon, 2002-12-23 at 10:00, Ronald W. Heiby wrote:
> I've got a large data compilation application. It takes in a very
> large quantity of text data and produces a resulting binary file that
> is about 1.3 GB. In the mean time, it holds on the order of 2 GB of
> data in memory while operating on it to produce the output file.

I also found 8.0 much slower for my smaller builds.  One thing that's
different in 8.0 is the ext3 filesystem, which I converted to when
upgrading.  By default it runs in ordered data mode, which causes writes
to disk to happen much more frequently than on ext2 filesystems.  

This is normally a goodness, because if your system crashes it takes
much less time to reboot with a working filesystem.  For a build system,
however, it's okay to crash in the middle of a build because it is (or
should be) easy to start over with a clean data set.  The ext3
filesystem supports a writeback mode which works well for me.

To turn writeback on, you need to add "data=writeback" to the build
partition's flags in fstab.  IMPORTANT: if you are setting the root
partition, you need to run /sbin/mkinitrd so your initrd file has the
same setting (either overwrite the one in /boot, or create a new one and
change your grub or lilo file to point to it).

Keep a rescue disk handy when you commit these changes!

Tom







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