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

Jesse Barnes
2004-06-16T16:27:54Z

On Wednesday, June 16, 2004 12:07 pm, Christoph Hellwig wrote:
> Well, if you want deterministic interrupt latencies you should go for a
> realtime OS.

Although I don't want to see another kernel thread added as much as the next
guy, I think that minimizing the amount of time that irqs are turned off is
probably a good thing in general. For example, the patch to allow interrupts
in spin_lock_irq if the lock is already taken is generally a really good
thing, because even though reducing lock contention should be a goal, locks
by their very nature are taken sometimes, and allowing other CPUs to get
useful work done while they're waiting for it is obviously desirable.

> I know Linux is the big thing in the industry, but you're
> really better off looking for a small Hard RT OS.

Sure, for some applications, an RTOS is necessary. But it seems like keeping
latencies down in Linux is a good thing to do nonetheless.

Can you think of other ways to reduce the length of time that interrupts are
disabled during cache reaping? It seems like the cache_reap loop might be a
candidate for reorganization (though that would probably imply other
changes).

Thanks,
Jesse