Re: Results of using tar with 2.5.[60 63 62-mm3] and reiser[fs 4], ext3, xfs.

From: Hans Reiser (reiser@namesys.com)
Date: Thu Feb 27 2003 - 15:15:43 EST


Steven Cole wrote:

>
>Brief summary: It looks like the order of performance for this
>particular load is reiserfs, reiser4, ext3, xfs.
>

The performance of reiserfs V3 relative to ext3 and XFS in this
benchmark is consistent with past experience as best I can remember it.
I would say that roughly speaking these results have been true without
major change during the period we have been testing (at least for
writes, ext3 does better on reads, and I won't predict which of ext3 or
reiserfs is currently faster for reads, ext3 has tended to have a slight
read speed advantage for linux kernel source code).

The ~6% disadvantage of V4 compared to V3 is a bit surprising, and we
are still evaluating that result. We just checked in a complete rewrite
of the flushing code today: give us a few weeks of analysis and we will
hopefully have better results for V4 versus V3. The primary purpose of
the rewrite was code clarity, but rumor has it we found unnecessary work
being done during the rewrite and corrected it.;-) With clear code it
will be easier for us to analyze what it is doing.

I would advise using a larger benchmark with 30-60 kernels being
copied. Filesystems sometimes perform differently for sync than for
memory pressure.

I would be interested to understand why ext3 is slower for sync: is it
because it has more in its write cache, or because of something else?
If it has more in its write cache, then our write caching is less
aggressive in reiser4 than I want it to be, and if it is something else
then the ext3 guys need to look into it.

Thanks for doing this test.

-- 
Hans

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