lkml.org 
[lkml]   [2004]   [Dec]   [15]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateWed, 15 Dec 2004 09:52:57 +0100
FromIngo Molnar <>
SubjectRe: [patch, 2.6.10-rc3] safe_hlt() & NMIs
* Linus Torvalds <torvalds@osdl.org> wrote:

> > find the correct patch below. I've tested it with an NMI watchdog
> > frequency artificially increased to 10 KHz, and i've instrumented the
> > new branch in the NMI handler, but even under heavy IRQ load i was not
> > able to trigger the branch. Maybe newer CPUs handle this case somehow
> > and make sti;hlt truly atomic?
> 
> Now that you mention it, I have this dim memory of the one-instruction
> "sti-shadow" actually disabling NMI's (and debug traps) too. The CPU
> literally doesn't test for async events following "sti". 

i ran the stresstest overnight with the 10 KHz NMI, and not a single
time did the new branch trigger, out of hundreds of millions of IRQs and
NMIs. I think this suggests that the race doesnt exist in current CPUs.

	Ingo
-
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/

\
 
 \ /
  Last update: 2005-03-22 14:08    [from the cache]
©2003-2008