[SRU] Set the default IO scheduler to CFQ in Kubuntu Trusty
Colin Ian King
colin.king at canonical.com
Wed Oct 8 16:42:48 UTC 2014
-----BEGIN PGP SIGNED MESSAGE-----
On 08/10/14 17:36, Steve Langasek wrote:
> Hi Jonathan,
> On Wed, Oct 08, 2014 at 03:56:42PM +0100, Jonathan Riddell wrote:
>> Me and Rohan would like a second opinion on bug 1378789
>> [SRU] Set the default IO scheduler to CFQ in Kubuntu Trusty
>> The kernel team have changed the scheduler away from upstream Linux
>> defaults to deadlock which causes our desktop indexing programme Baloo
>> to run very slow and take up lots of resources because it doesn't
>> implement ionice suport. We'd like to update kubuntu-settings with a
>> udev rule to change back to CFQ.
>> We've changed this in utopic. There's minimal chance of regressions,
>> it's an upstream default recommended by Linux and Baloo. We're
>> getting quite a few reports of people saying their system is sluggish
>> and the baloo upstream author is most grumpy.
>> Scott would rather wait until after utopic is out where it would get
>> more testing, but I doubt there will be much that most users can say
>> beyond "it's not horribly slow".
> I don't think it's at all appropriate for a desktop environment to install a
> udev rule which changes the kernel scheduler. That's a severe layering
> violation, and it means that anyone who installs kubuntu-desktop on an
> existing system will significantly change the performance characteristics of
> that system.
> I also think it's categorically wrong to say that there's minimal chance of
> regression. These schedulers have pretty fundamentally different
> characteristics, and where CFQ behaves pathologically for one process (the
> indexer), deadline will behave pathologically for others.
> I don't think it's at all acceptable to work around a kernel bug in a
> kubuntu-settings SRU. The right fix is to resolve this in the kernel
> package instead. (Bug #1310402) Cc:ing the kernel team.
> Also, what exactly do you mean when you say baloo doesn't "implement ionice
> support"? The 'ionice' tool is part of the base system (util-linux). It
> would be a simple matter of packaging to always run baloo under ionice.
Linux supports I/O scheduling priorities since 2.6.13 just with the CFQ
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
-----END PGP SIGNATURE-----
More information about the kernel-team