From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Lee Revell <rlrevell@joe-job.com>,
Andrea Arcangeli <andrea@suse.de>,
Manfred Spraul <manfred@colorfullife.com>,
Zwane Mwaikambo <zwane@arm.linux.org.uk>,
George Anzinger <george@mvista.com>,
dipankar@in.ibm.com, ganzinger@mvista.com,
lkml <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>, Andi Kleen <ak@suse.de>
Subject: Re: [patch, 2.6.10-rc3] safe_hlt() & NMIs
Date: Wed, 15 Dec 2004 09:52:57 +0100 [thread overview]
Message-ID: <20041215085257.GA12545@elte.hu> (raw)
In-Reply-To: <Pine.LNX.4.58.0412141501250.3279@ppc970.osdl.org>
* 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
next prev parent reply other threads:[~2004-12-15 8:53 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-09 23:59 RCU question George Anzinger
2004-12-10 4:31 ` Dipankar Sarma
2004-12-10 19:42 ` George Anzinger
2004-12-10 20:40 ` Dipankar Sarma
2004-12-10 20:45 ` Lee Revell
2004-12-10 21:02 ` George Anzinger
2004-12-10 22:58 ` Zwane Mwaikambo
2004-12-11 2:22 ` George Anzinger
2004-12-11 2:45 ` Zwane Mwaikambo
2004-12-11 3:29 ` George Anzinger
2004-12-11 14:52 ` Zwane Mwaikambo
2004-12-11 16:32 ` Manfred Spraul
2004-12-11 16:52 ` George Anzinger
2004-12-12 2:53 ` Zwane Mwaikambo
2004-12-12 8:59 ` Manfred Spraul
2004-12-12 9:37 ` Andrea Arcangeli
2004-12-12 10:22 ` Manfred Spraul
2004-12-12 12:15 ` Andrea Arcangeli
2004-12-14 21:40 ` Lee Revell
2004-12-14 22:23 ` [patch, 2.6.10-rc3] safe_hlt() & NMIs Ingo Molnar
2004-12-14 22:47 ` Ingo Molnar
2004-12-14 23:09 ` Linus Torvalds
2004-12-15 8:52 ` Ingo Molnar [this message]
2004-12-15 15:44 ` Linus Torvalds
2004-12-15 16:35 ` Ingo Molnar
2004-12-16 0:37 ` Alan Cox
2004-12-16 1:58 ` Linus Torvalds
2004-12-16 14:51 ` Ingo Molnar
2004-12-16 15:08 ` Maciej W. Rozycki
2004-12-16 15:11 ` Ingo Molnar
2004-12-16 15:42 ` Maciej W. Rozycki
2004-12-16 15:54 ` Linus Torvalds
2004-12-16 2:10 ` Zwane Mwaikambo
2004-12-16 13:26 ` Alan Cox
2004-12-14 23:41 ` Andrea Arcangeli
2004-12-14 23:00 ` Linus Torvalds
2004-12-15 5:04 ` Andi Kleen
2004-12-15 6:27 ` Avi Kivity
2004-12-15 8:51 ` Ingo Molnar
2004-12-12 16:51 ` RCU question George Anzinger
2004-12-12 22:40 ` Manfred Spraul
2004-12-13 5:22 ` George Anzinger
2004-12-12 16:26 ` Zwane Mwaikambo
-- strict thread matches above, loose matches on Subject: below --
2004-12-17 23:35 [patch, 2.6.10-rc3] safe_hlt() & NMIs Chuck Ebbert
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