Neil Brown wrote:

On Friday December 8, neilb@suse.de wrote:
  

quoted

I have measured very slow write throughput for raid5 as well, though
2.6.18 does seem to have the same problem.  I'll double check and do a
git bisect and see what I can come up with.
    

Correction... it isn't 2.6.18 that fixes the problem.  It is compiling
without LOCKDEP or PROVE_LOCKING.  I remove those and suddenly a
3 drive raid5 is faster than a single drive rather than much slower.

Bill:  Do you have LOCKDEP or PROVE_LOCKING enabled in your .config ??
  

I have to check tomorrow, I'm using the Fedora kernel (as noted in the 
first post on this) rather than one I built, just so others could verify 
my results as several have been kind enough to do. Have to run, but I 
will check tomorrow or Monday morning early at the latest.

-- 
bill davidsen [off-list ref]
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979