On Thu, Aug 21, 2008 at 05:53:10AM -0600, Matthew Wilcox wrote:
Not obviously the same sort of issue. The traces clearly show
multiple nested dispatches and completions so CTQ is definitely
active...
Anyway, after a teeth-pulling equivalent exercise of finding the
latest firmware for the machine in a format I could apply, I
upgraded the firmware throughout the machine (disks, raid
controller, system, etc) and XFS is a *lot* faster. In fact -
mostly back to +/- a small amount compared to ext3.
run complete:
==========================================================================
avg MB/s user sys
runs xfs ext3 xfs ext3 xfs ext3
intial create total 30 6.36 6.29 4.48 3.79 7.03 5.22
create total 7 5.20 5.68 4.47 3.69 7.34 5.23
patch total 6 4.53 5.87 2.26 1.96 6.27 4.86
compile total 9 16.46 9.61 1.74 1.72 9.02 9.74
clean total 4 478.50 553.22 0.09 0.06 0.92 0.70
read tree total 2 13.07 15.62 2.39 2.19 3.68 3.44
read compiled tree 1 53.94 60.91 2.57 2.71 7.35 7.27
delete tree total 3 15.94s 6.82s 1.38 1.06 4.10 1.49
delete compiled tree 1 24.07s 8.70s 1.58 1.18 5.56 2.30
stat tree total 5 3.30s 3.22s 1.09 1.07 0.61 0.53
stat compiled tree total 3 2.93s 3.85s 1.17 1.22 0.59 0.55
The blocktrace looks very regular, too. All the big bursts of
dispatch and completion are gone as are the latencies on
log I/Os. It would appear that ext3 is not sensitive to
concurrent I/O latency like XFS is...
At this point, I'm still interested to know if the original
results were had ctq/ncq enabled and if it is whether it is
introducing latencies are not.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
--
