Re: [Jfs-discussion] benchmark results

Christian Kujau
2009-12-25T01:52:34Z

On Thu, 24 Dec 2009 at 16:27, tytso@mit.edu wrote:
> If you don't do a "sync" after the tar, then in most cases you will be
> measuring the memory bandwidth, because data won't have been written

Well, I do "sync" after each operation, so the data should be on disk, but
that doesn't mean it'll clear the filesystem buffers - but this doesn't
happen that often in the real world too. Also, all filesystem were tested
equally (I hope), yet some filesystem perform better than another - even
if all the content copied/tar'ed/removed would perfectly well fit into the
machines RAM.

> Another good example of well done file system benchmarks can be found
> at http://btrfs.boxacle.net

Thanks, I'll have a look at it and perhaps even integrate it in the
wrapper script.

> benchmarks for a living. Note that JFS and XFS come off much better
> on a number of the tests

Indeed, I was surpised to see JFS perform that good and XFS of course is
one of the best too - I just wanted to point out that both of them
are strangely slow at times (removing or creating many files) - not what I
expected.

> --- and that there is a *large* number amount
> of variation when you look at different simulated workloads and with a
> varying number of threads writing to the file system at the same time.

True, the TODO list in the script ("different benchmark options") is in
there for a reason :-)

Christian.
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