Lossy interrupts on x86_64

From: Jesse Barnes
Date: Wed Sep 12 2007 - 11:40:42 EST


I just narrowed down a weird problem where I was losing more than 50% of
my vblank interrupts to what seems to be the hires timers patch. Stock
2.6.23-rc5 works fine, but the latest (171) kernel from rawhide drops
most of my interrupts unless I also have another interrupt source
running (e.g. if I hold down a key or move the mouse I get the expected
number of vblank interrupts, otherwise I get between 3 and 30 instead
of the expected 60 per second).

Any ideas? It seems like it might be bad APIC programming, but I
haven't gone through those mods to look for suspects...

Thanks,
Jesse
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