Messages in this thread |  | | | Date | Wed, 30 Jul 2003 22:40:52 +0300 | | From | Ville Herva <> | | Subject | Re: [PATCH] NMI watchdog documentation |
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On Wed, Jul 30, 2003 at 09:20:33PM +0200, you [Mikael Pettersson] wrote: > On Tue, 29 Jul 2003 20:53:19 +0300, Ville Herva wrote: > >On Tue, Jul 29, 2003 at 06:06:30PM +0200, you [Andi Kleen] wrote: > >> > Andi, you have the numbers mixed up. mode 1 is I/O-APIC, mode 2 is local APIC, > >> > and x86-64 defaults nmi_watchdog to I/O-APIC mode. > >> > Now, is it the I/O-APIC or local APIC watchdog that doesn't work in x86-64? > >> > >> Right, 1 and 2 need to be exchanged. Anyways local apic mode does not seem > >> to work, the kernel always reportss "NMI stuck" at bootup. > >> IO APIC mode for is default. > ... > >+For x86-64, the needed APIC is always compiled in, and the NMI watchdog is > >+always enabled with perfctr mode. Currently, mode=1 does not work on x86-64. > > Didn't Andi just say it's the other way around? nmi_watchdog=1 (I/O-APIC) > by default since nmi_watchdog=2 (local APIC) doesn't work.
Ok, you got me confused (thankfully I didn't submit anything for inclusion yet. :)
Initially, Andi said:
http://marc.theaimsgroup.com/?l=linux-kernel&m=105941508314399&w=2 > x86-64 is the same, except APIC is always compiled in and the nmi watchdog > is always enabled with perfctr mode. mode=2 seems to also not work > correctly currently. > > However one caveat (even for i386): when you use perfctr mode 1 you lose > the first performance register which you may need for other things.
To which I replied: http://marc.theaimsgroup.com/?l=linux-kernel&m=105942026020567&w=2 > So, is something like the following ok by you > > +For x86-64, the needed APIC is always compiled in, and the NMI watchdog is > +always enabled with perfctr mode. Currently, mode=2 does not work on x86-64. > + > +Using NMI watchdog (in mode=1) needs the first performance register, so you > +can't use it for other purposes (such as high precision performance > +profiling.)
But you pointed out it was the other way around: http://marc.theaimsgroup.com/?l=linux-kernel&m=105947532631384&w=2 > Andi, you have the numbers mixed up. mode 1 is I/O-APIC, mode 2 is local > APIC, and x86-64 defaults nmi_watchdog to I/O-APIC mode. Now, is it the > I/O-APIC or local APIC watchdog that doesn't work in x86-64?
And Andi agreed: http://marc.theaimsgroup.com/?l=linux-kernel&m=105949540722325&w=2 > Right, 1 and 2 need to be exchanged. Anyways local apic mode does not seem > to work, the kernel always reportss "NMI stuck" at bootup. IO APIC mode > for is default.
So I proposed (blindly exchanging the numbers): http://marc.theaimsgroup.com/?l=linux-kernel&m=105950174531125&w=2 > +For x86-64, the needed APIC is always compiled in, and the NMI watchdog is > +always enabled with perfctr mode. Currently, mode=1 does not work on x86-64. > + > +Using NMI watchdog (in mode=2) needs the first performance register, so you > +can't use it for other purposes (such as high precision performance > +profiling.)
So... Should it be something like:
+For x86-64, the needed APIC is always compiled in, and the NMI watchdog is +always enabled with perctr mode. Currently, mode=2 (local APIC) does not +work on x86-64. IO APIC mode (mode=1) is the default. Using NMI watchdog +(mode=1) needs the first performance register, so you can't use it for +other purposes (such as high precision performance profiling.)
(Is the last sentence only valid for x86-64?)
-- v --
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