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* CPU hotplug and IRQ affinity with 2.6.24-rt1
@ 2008-02-04 23:35 Max Krasnyanskiy
  2008-02-05  2:51 ` Daniel Walker
  0 siblings, 1 reply; 11+ messages in thread
From: Max Krasnyanskiy @ 2008-02-04 23:35 UTC (permalink / raw)
  To: LKML; +Cc: Ingo Molnar, Daniel Walker

This is just an FYI. As part of the "Isolated CPU extensions" thread Daniel suggest for me
to check out latest RT kernels. So I did or at least tried to and immediately spotted a couple
of issues.

The machine I'm running it on is:
	HP xw9300, Dual Opteron, NUMA

It looks like with -rt kernel IRQ affinity masks are ignored on that system. ie I write 1 to 
lets say /proc/irq/23/smp_affinity but the interrupts keep coming to CPU1. 
Vanilla 2.6.24 does not have that issue.

Also the first thing I tried was to bring CPU1 off-line. Thats the fastest way to get irqs, 
soft-irqs, timers, etc of a CPU. But the box hung completely. It also managed to mess up my 
ext3 filesystem to the point where it required manual fsck (have not see that for a couple of
years now). 
I tried the same thing (ie echo 0 > /sys/devices/cpu/cpu1/online) from the console. It hang 
again with the message that looked something like:
	CPU1 is now off-line
	Thread IRQ-23 is on CPU1 ...

IRQ 23 is NVidia SATA. So I guess it has something to do with the borked affinity handling.
Vanilla 2.6.24 handles this just fine.

Anyway, like I said it's just an FYI, not an urgent issue.

Max


^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2008-02-05 22:10 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2008-02-04 23:35 CPU hotplug and IRQ affinity with 2.6.24-rt1 Max Krasnyanskiy
2008-02-05  2:51 ` Daniel Walker
2008-02-05  3:27   ` Gregory Haskins
2008-02-05  4:21   ` Max Krasnyansky
2008-02-05  5:02   ` Gregory Haskins
2008-02-05 16:59     ` Daniel Walker
2008-02-05 17:13       ` Gregory Haskins
2008-02-05 18:25       ` Gregory Haskins
2008-02-05 21:58         ` Daniel Walker
2008-02-05 22:03           ` Gregory Haskins
2008-02-05 14:00   ` Gregory Haskins

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