[mythtv] [mythtv-commits] Ticket #1791: Stop transcode/commflag from hogging the CPU while recording/playback is in progress.
Stuart Auchterlonie
stuarta at squashedfrog.net
Tue Sep 19 08:15:46 UTC 2006
On Tue, Sep 19, 2006 at 03:29:52AM -0400, f-myth-users at media.mit.edu wrote:
> > Date: Thu, 14 Sep 2006 21:22:11 +0200
> > From: Daniel Staaf <dst at bostream.nu>
>
> > f-myth-users at media.mit.edu wrote:
> > >
> > > Some more research -seems- to indicate that the Breezy kernel these
> > > machines run might be fixable simply by adding
> > > elevator=cfq
> > > to the boot line, and adding
> > > # nonaltoptions=quiet splash elevator=cfq
> > > so it winds up on kernel updates as well. I'm hoping that this is
> > > true, since I'd rather not have to compile a non-stock kernel (as
> > > your example seems to indicate).
> > >
> > > It also appears I can change this on the fly with
> > > echo cfq > /sys/block/hdX/queue/scheduler
> > > per-disk, and check the current setting for all disks with
> > > cat /sys/block/hd*/queue/scheduler
> > > so I may be able to screw around with this without even rebooting.
>
> > Yes, no need to recompile.
>
> Well, I tried "echo cfq > /sys/block/hdX/queue/scheduler", for X=a or c
> on both of my machines. It doesn't appear to have made -any- difference;
> even though "cat /sys/block/hd*/queue/scheduler" now reported that all
> 4 disks were using CFQ, my stress-test still provoked exactly the same
> glitches when the scheduler ran, e.g., if I'm recording on multiple
Have you tried the deadline scheduler?
It guarantees i/o response within a certain timeframe (ie. deadline)
I've found it works the best for me.
Stuart
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