Re: Real-time problem due to IO congestion.

[Lee Revell <rlrevell@joe-job.com>]

On Fri, 2005-06-10 at 16:49 +0900, Takashi Ikebe wrote:
> Jens Axboe wrote:
> > On Fri, Jun 10 2005, Takashi Ikebe wrote:
> > 
> > This basically needs io priorities to work, so that request allocation
> > is prioritized as well. I didn't actually add request allocation groups
> > in the cfq-ts posted with priority support, however I have some patches
> > from years ago that did so. I'll see if I can find the time to brush
> > those off.
> > 
> 
> As you and andrew said, basically application based approach seems 
> reasonable,
> but I'm so interesting your patch, if you have time, please show me :-)

Take a look at the lock-free ringbuffers in JACK.  No point reinventing
the wheel...

I think it's a bit strange that the disk IO issue comes up so often in
these RT discussions, it's something of a red herring, because there's
rarely an RT constraint in getting the data to disk; the RT constraint
is in getting the data from the device to memory.

Lee