On Wed, Jun 24, 2009 at 03:59:14AM -0700, David Miller wrote: > From: Andi Kleen <andi@xxxxxxxxxxxxxx> > Date: Wed, 24 Jun 2009 12:52:23 +0200 > > > On Wed, Jun 24, 2009 at 03:32:33AM -0700, David Miller wrote: > >> From: Andi Kleen <andi@xxxxxxxxxxxxxx> > >> Date: Wed, 24 Jun 2009 12:23:25 +0200 > >> > >> >> And similarly to sparc64, if that 5+ second qla2xxx interrupt > >> >> sequence happens after the tick_nohz_stop_sched_tick() call > >> >> we can run into the same situation. > >> > > >> > Yes it would be probably safer to do the tick disabling with > >> > interrupts off already. > >> > >> That only makes sense if you're really putting the cpu to sleep > >> until an interrupt or similar happens. > > > > That is what the idle loop is supposed to do, isn't it? > > Some sparc64 cpu's don't have a yield, and therefore can't > truly "sleep" during this loop. That's what I'm talking > about. How are power saving states invoked instead? Or do they not having any power saving idle states? > >> > These days NMI watchdog is not used much on x86 anymore because it's > >> > default off, so probably people never noticed that. > >> > >> I really didn't want to provide the feature that way on sparc64 which > >> is why I made it on by default. It would be interesting to reconsider > >> x86's default, perhaps even only on a trial basis in -next. > > > > The reason it was turned off is that there are a few systems (e.g. > > laptops from a particular vendor) which don't handle NMIs correctly > > in the platform. When the NMI happens while SMI is active > > they hang. Also there were a few other strange problems > > on other systems that went away when it was disabled. > > I wonder how many of those "few other strange problems" were of > the variety I'm diagnosing here :-) Some likely. But the general problem is that hardware architects do not normally consider NMIs as owned by the OS, but rather as owned by the platform. > Is this realm of systems-with-NMI-issues exclusive to x86-32 > or would it be more doable to turn it on by default for 64-bit > x86 builds? Some of these problems were on 64bit capable systems. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
