Messages in this thread | | | Date | Mon, 04 Feb 2008 15:35:13 -0800 | From | Max Krasnyanskiy <> | Subject | CPU hotplug and IRQ affinity with 2.6.24-rt1 |
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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
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