Re: Blogbench RAID benchmarks

[Freddie Cash <fjwcash@xxxxxxxxx>]

On Mon, Jul 18, 2011 at 7:06 PM, Matthew Dillon <dillon@apollo.backplane.com> wrote:

   Ok, well this is interesting.  Basically it comes down to whether we
   want to starve read operations or whether we want to starve write
   operations.

   The FreeBSD results starve read operations, while the DragonFly results
   starve write operations.  That's the entirety of the difference between
   the two tests.

Would using the disk scheduler's in FBSD/DFly help with this at all?

FreeBSD includes a geom_sched class for enabling pluggable disk scheduler's (currently only round-robin algorithm is implemented).  http://info.iet.unipi.it/~luigi/geom_sched/

And I believe DFly has dsched?

 

   This is all with swapcache turned off.  The only way to test in a
   fair manner with swapcache turned on (with a SSD) is if the FreeBSD
   test used a similar setup w/ZFS.

ZFS includes it's own disk scheduler, so geom_sched wouldn't help in that case.  Would be interesting to see a comparison of HAMMER+swapcache and ZFS+L2ARC, though.

-- 
Freddie Cash
fjwcash@gmail.com