Re: mkfs.xfs questions

[David Chinner <dgc@sgi.com>]

On Tue, Dec 05, 2006 at 05:46:15PM +0000, Christian Kujau wrote:
> On Sat, 2 Dec 2006, Iustin Pop wrote:
> >Hmm, I am pretty sure that it makes a difference, but only from personal
> >experience, not from benchmarks. A while ago, mkfs.xfs used to make <8M
> >logs even for big filesystems[0]. Nowadays it chooses a more sane value.
> 
> I could not stand my own curiosity, so here it is: 
> http://nerdbynature.de/wp/?cat=4

One line summary:

"The results however are a bit boring and I for one have no reason to tweak
these options for a desktop machine."

For that data set size you tested. However you might find a
difference if your tests actually write the data back to disk
because a lot of the tests are running out of cache.

> I think I'll repeat the benchmarks with bigger test sizes. The 
> testscript can easily be adjusted to test more options/values.

I think you need to to have any hope of demonstrating a
difference in performance from the mkfs/mount options.

Typically, you need to be writing/reading files at least 2x the
size of memory and create/delete a fileset of at least 1,000,000
files to really determine differences in performance from
these parameters...

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group