bfriesen at simple.dallas.tx.us
Wed Oct 12 19:39:43 UTC 2011
On Wed, 12 Oct 2011, Jeremy Chadwick wrote:
> That might be the case on OpenSolaris but the performance hit on
> FreeBSD RELENG_8 is very high -- enough that enabling compression (using
> the defaults) causes stalls when I/O occurs (easily noticeable across
> SSH; characters are delayed/stalled (not buffered)), etc..
Solaris solved the problem by putting the zfs writer threads into a
special scheduling class so that they are usually lower priority than
normal processing. Before this change, a desktop system would become
almost unusable (intermittent loss of keyboard/mouse) while writing
lots of data with compression enabled. Some NFS servers encountered
severe enough issues that NFS clients reported NFS timeouts.
> Another point: I haven't tinkered with compression on our Solaris 10
> machines at work so I don't know if it performs better, equal, or worse
> than FreeBSD or OpenSolaris.
>From what you describe, Solaris must be doing much better in this
regard than FreeBSD. Solaris is not necessarily faster but there is
now little impact on interactive tasks.
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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