responsiveness during IO tasks
Doug Barton
dougb at FreeBSD.org
Wed Apr 27 23:44:13 UTC 2011
On 04/26/2011 03:37, Alexander Best wrote:
> On Mon Apr 25 11, Steve Wills wrote:
> Hi,
>
> I've noticed lately that when doing heavy IO, my 9-CURRENT system (Fri
> Apr 15 23:33:46 EDT 2011) is quite unresponsive. I have two ZFS mirrors
> setup and run KDE4. The system has 12GB of RAM.
>
> When I, for example, copy an ISO image from one mirror to the other, the
> whole desktop becomes really slow during the copy. It takes a good 15
> seconds to open a new tab in Konsole, switching windows takes a while,
> etc. Once the copy is finished, things are fine. It wasn't like this
> back before I upgraded from 8.2-RC1 to 9-CURRENT. Has anyone else
> noticed something similar, or is it just me? Is there any other info I
> can provide or something I should look for?
>
>> i've noticed this too. for me the situation is sometimes even worse. during
>> heavy i/o the mouse cursor won't even respond.
>
>> i think this is a scheduler isse. maybe running a non-preemptive kernel or
>> switching to the old 4bsd scheduler fixes it?
Try backing up your src tree to r212540, clean /usr/obj,
buildworld/kernel and see if that helps. I just tracked down a big part
of my current problem (pun intended) to r212541, the one-shot timer
commit. I'm working on a larger post to describe my problems, but short
version is, up through r212540 I can load the system down as heavily as
I want, and while there may be some unresponsiveness it's at least
stable. If I update to one-shot timers the system wedges as soon as I
put load on it. No panic, not even a reboot, it just wedges solid
requiring it to be powered off.
You should also test SCHED_4BSD to see if that improves your situation.
There have been a lot of reports about problems with SCHED_ULE with
heavy disk i/o. Moving to 4bsd helps me in terms of interactivity, but I
needed to find the crashing problem first.
hth,
Doug (sorry mav)
--
Nothin' ever doesn't change, but nothin' changes much.
-- OK Go
Breadth of IT experience, and depth of knowledge in the DNS.
Yours for the right price. :) http://SupersetSolutions.com/
More information about the freebsd-current
mailing list