Reiser4 status: benchmarked vs. V3 (and ext3)

Please look at http://www.namesys.com/benchmarks/v4marks.html

In brief, V4 is way faster than V3, and the wandering logs are indeed twice
as fast as fixed location logs when performing writes in large batches.

We are able to perform all filesystem operations fully atomically, while
getting dramatic performance improvements.  (Other attempts at introducing
transactions into filesystems are said to have failed for performance
reasons.)

Balancing at flush time works well, not using blobs works well, allocating
at flush time works well.  CPU time is good enough to get by, and it will
improve over the next few months as we tweak a lot of little details, but
the IO performance is what matters, and this performance is quite good
enough to use.  In all the places where V3 sacrifices performance to save
disk space, V4 saves more disk space and gains rather than loses
performance. The plugin infrastructure works well, expect lots of plugins
over the next year or two.

Look for a repacker to come out in a few weeks that will make these numbers
especially good for filesystems that have 80% of their files unmoving for
long periods of time (which is to say most systems), and might otherwise
suffer from fragmentation.

These benchmarks mean to me that our performance is now good enough to ship
V4 to users (which means we need persons willing to try to crash it so that
the stability can become good enough to ship to users).  Sometime during
the next week or two we will probably send a patch in, and ask for
inclusion.  We need to run another round of stress tests after our latest
tweaks, and kill off two bugs that got added just recently, and then we
will ask for testers. I will be going to Budapest to discuss filesystem
semantics with Peter Foldiak for a week, so V4 may get sent in for
inclusion by members of my team while I am absent.  If so, please include
it in 2.5/2.6.

-- 
Hans


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