A specific example of a disk i/o problem (was: FreeBSD vs
attilio at freebsd.org
Wed Sep 30 06:30:35 UTC 2009
2009/9/30 Dieter <freebsd at sopwith.solgatos.com>:
>> > My question is why is FreeBSD's disk i/o performance so bad?
>> As I mentioned... this was discussed actively in slashdot. You will find
>> there many good comments on this.
> All I saw in slashdot was a ffs vs ext comment. I don't believe the problems
> I'm seeing are filesystem related.
>> > Not just in the benchmarks with debugging on, but in real world usage
>> > where it actually matters.
>> Are you saying this from actual experience or from reading other people's
> Here is a specific demo of one disk i/o problem I'm seeing. Should be
> easy to reproduce?
> This was over a year ago, so add 7.1 to the list of versions with the problem.
> I believe that the
> swap_pager: indefinite wait buffer: bufobj: 0, blkno: 1148109, size: 4096
> messages I'm getting are the same problem. A user process is hogging
> the bottleneck (disk buffer cache?) and the swapper/pager is getting starved.
Sorry, do you have a PR/describing e-mail with this issue? Can you be
a bit more precise?
The problem reported in the earlier post, however, is interesting and
worths more analysis.
More speficially, would you be interested in reproducing and playing a
bit with some diagnostic tool/configurations I can point you at?
Peace can only be achieved by understanding - A. Einstein
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