Am Montag 23 Juni 2008 schrieb Mark:
> I ran a round of tests using 5 threads, to resemble 1 runnable and 1
> waiting on each CPU, plus 1 more waiting. In other words, lightly
> overloaded. XFS was the clear winner, with 378 MB/sec using the "noop"
> scheduler. The "deadline" scheduler was a close second, with 371
> Here was the first twist: The completely fair queueing (CFQ) scheduler
> seriously impeded XFS performance, so badly that even "noop"
> out-performed it when the CPU was running at 40% clock.
> I re-ran all tests with 20 threads, to simulate severe process I/O
> overloading. Even on my 2-CPU system, XFS scaled somewhat, achieving
> 403 MB/sec with "deadline" and 401 MB/sec with "anticipatory." CFQ
> didn't hurt the throughput as much this time, but it still came in last
> (263 MB/sec).
Thats interesting. I was curious and thus switched from cfq to deadline
scheduler during parallel I/O workload on my ThinkPad T42 (aptitude
upgrade / kmail receiving mails from POP3 account).
It subjectively feeled way faster with deadline. I always wondered about
the slowness of my ThinkPad T42 at massive parallel I/O. Now it feels a
lot more responsive. Its as if I bought a new super-seek harddisk or what
(compared to before).
I think I will try deadline for some days at least, also on my ThinkPad
T23 and on my workstation at work.
No objective performance measurements yet. ;) And not much time for them
Have I/O schedulers been tested against different filesystems before?
Maybe the default I/O scheduler cfq isn't the best one for XFS, but only
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
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