From: | "Dmitrij D. Czarkoff" <czarkoff@xxxxxxxxx> |
Date: | Tue, 20 Dec 2011 13:50:53 +0100 |
On Tue, Dec 20, 2011 at 10:07:22AM +0100, Francois Tigeot wrote: > Most of the VFS accounting work is now in the tree (and disabled by default, > enable it with vfs.accounting_enabled="1" in /boot/loader.conf). > Only a potentially disruptive commit to enable it for / has not been pushed. > > Since VFS accounting uses a per mount-point spinlock to protect its counters, > there is some concern it will degrade write performance on SMP machines. > > To measure if this was the case or not, I've run some blogbench benchmarks on > a small Xeon system; the details of the test and the results are in the > attached PDF. > > VFS accounting kernel was from 2011-12-19 > Kernel without VFS accounting was from 2011-11-19 > > For my part I think the results are inconclusive: either there's no measurable > performance difference or the choice of benchmark was bad. I've made a plot which shows the results in more evident way (if I correctly understand the test results data). -- Dmitrij D. Czarkoff
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