Re: [PATCH]: Option to run cache reap in thread mode

Christoph Hellwig
2004-06-16T16:07:14Z

On Wed, Jun 16, 2004 at 11:03:55AM -0500, Dimitri Sivanich wrote:
> On Wed, Jun 16, 2004 at 04:29:34PM +0100, Christoph Hellwig wrote:
> > YAKT, sigh.. I don't quite understand what you mean with a "holdoff" so
> > maybe you could explain what problem you see? You don't like cache_reap
> > beeing called from timer context?
>
> The issue(s) I'm attempting to solve is to achieve more deterministic interrupt
> response times on CPU's that have been designated for use as such. By setting
> cache_reap to run as a kthread, the cpu is only unavailable during the time
> that irq's are disabled. By doing this on a cpu that's been restricted from
> running most other processes, I have been able to achieve much more
> deterministic interrupt response times.
>
> So yes, I don't want cache_reap to be called from timer context when I've
> configured a CPU as such.

Well, if you want deterministic interrupt latencies you should go for a realtime OS.
I know Linux is the big thing in the industry, but you're really better off looking
for a small Hard RT OS. From the OpenSource world eCOS or RTEMS come to mind. Or even
rtlinux/rtai if you want to run a full linux kernel as idle task.