On Mon, 5 Jul 2004, Kirk Strauser wrote:
>
> > here's the fun freebie script to test which filesystem is faster
> > - format the disk(partitions) once
> > - do 3 passes copying 2.3GB of files from /dev/hda to /dev/hdc
>
> Your benchmark is fundamentally skewed. It uses tar to copy files from your
> root dirctory to $MNT without caching the intermediate tarballs. This means
> that in each case, you're also measuring the read speed of your normal
> filesystems in addition to the write speed of your target. In the first
> pass, you're also timing the speed at which your filesystems can fill their
> directory listing caches, which will artificially improve subsequent runs.
thanx for looking at the "1st draft"
yes, on the cache issue .... i have not figured out how to clear the
cache between each pass
- umounting adn remounting it in the pass seems to help
when testing thruput of 10MB.file.tgz across a wireless link
- in the wireless tests, the 1st copy takes say 10minutes, but all
subsequent tests copied "data across the wireless link" in
5 seconds :-) ( unmounting and remounting the seems to make
each subsequent copy to come from the originating source instead
of the local cache on the target )
another few things that will throw off the "tests"
i have 1GB of memory ... and the data files is a mere 2.3GB,
which tells me the cache will have a big impact on thru put
vs the "performance of the target"
since i'm always copyig the "changing" master files, each
subsequent copying will have a few more lines in /var/log of
new data that wasnt there previous
( but compared to 2GB of data, a few lines shouldn't hurt any )
another tests to do is to run a "set of benchmark test"
on the target's filesystem instead of using the same
"master disk" to do all the tests onto the target
i have the 3-pass numbers ... but since with 3 passes, that's not enough
info and cache flushing will be another day's fun
- anyway .. it was a fun project for a few hours
- will re-run it for a 10pass run at 10 minute each on 5 filesystem types
( 500 minutes ) will put me to sleep
c ya
alvin
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