Jeff Weber wrote:
> I am looking for guidance on how much I can rely upon the Linux kernel and
> Xenomai schedulers to perform automatic load balancing, vs. how much I must
> load balance manually. My config:
>
> x86 SMP system with 2 CPUs
> Linux 2.6.35.10 + xenomai-2.5.5.2
> ISA hardware device with 1 IRQ
> Xenomai kernel module driver using old-style native API (may be ported to
> RTDM in the future)
> user space application with multiple Linux and Xenomai threads
> no effort [yet] to explicitly set CPU affinities for either Xenomai, nor
> Linux
> cat /proc/xenomai/affinity output = 000000ff
>
> question: From /proc/xenomai/stat , I see all Xenomai kernel driver and
> userspace threads running on only CPU0, though my IRQ handler is being
> balanced on both CPUs. Will Xenomai ever "balance" or "migrate" threads to
> other CPUs if the affinity mask allows this?
Xenomai does not make any load balancing, because a migration introduces
a huge latency, so, what you have to do is to set an affinity with just
one bit set. And changing affinity during a thread's life is not
recommended.
>
> question: Does the Linux scheduler assume it owns 100% of the cycles on CPU0
> (where all the Xenomai threads happen to be running), and thus make
> incorrect scheduling decisions for Linux threads on CPU0?
I am not sure, what does top say ?
--
Gilles.
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