Messages in this thread | | | Subject | RE: SCHED_RR and kernel threads | Date | Mon, 8 Nov 2004 12:50:37 -0800 | From | "Stephen Warren" <> |
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> From: Con Kolivas [mailto:kernel@kolivas.org] > Stephen Warren wrote: > > It appears that during times of high application CPU usage, some > > *kernel* threads don't get to run. > > ... > > This appears to be due to the fact that the kernel threads are all > > SCHED_OTHER, so our SCHED_RR user-space application trumps them! > > Don't run your userspace at SCHED_RR? The kernel threads are > SCHED_NORMAL precisely for the reason that you wont get real time > performance if the kernel threads rear their ugly heads, > albeit rarely.
We have actually set the kernel threads to priority SCHED_RR 50, and most user-space threads to SCHED_RR priority 50. Some critical user-space threads are above priority 50.
Won't this allow the kernel and user space threads to co-operate nicely all the time?
What is it specifically that will make kernel SCHED_RR threads cause non-real-time operation? If it's just a bunch of corner cases or odd conditions, we may be in an environment we can control so that doesn't happen...
I guess we could have most threads stay at SCHED_NORMAL, and just make the few critical threads SCHED_RR, but I'm getting a lot of push-back on this, since it makes our thread API a lot more complex.
-- Stephen Warren, Software Engineer, NVIDIA, Fort Collins, CO swarren@nvidia.com http://www.nvidia.com/ swarren@wwwdotorg.org http://www.wwwdotorg.org/pgp.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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