From: Ville Herva <vherva@niksula.hut.fi>
To: Andi Kleen <ak@suse.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] NMI watchdog documentation
Date: Mon, 28 Jul 2003 22:21:42 +0300 [thread overview]
Message-ID: <20030728192142.GR83336@niksula.cs.hut.fi> (raw)
In-Reply-To: <20030728195342.02913727.ak@suse.de>
On Mon, Jul 28, 2003 at 07:53:42PM +0200, you [Andi Kleen] wrote:
>
> 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.
Thanks.
So, is something like the following ok by you (patch is relative to -test2
nmi-watchdog.txt)? If it is, I'll send it to Linus and Marcelo.
-- v --
v@iki.fi
--- /usr/src/linux/Documentation/nmi_watchdog.txt Mon Jul 28 22:10:18 2003
+++ /usr/src/linux~/Documentation/nmi_watchdog.txt Mon Jul 28 22:18:10 2003
@@ -1,9 +1,11 @@
-Is your ix86 system locking up unpredictably? No keyboard activity, just
+[NMI watchdog is available for x86 and x86-64 architectures]
+
+Is your system locking up unpredictably? No keyboard activity, just
a frustrating complete hard lockup? Do you want to help us debugging
such lockups? If all yes then this document is definitely for you.
-On Intel and similar ix86 type hardware there is a feature that enables
+On many x86/x86-64 type hardware there is a feature that enables
us to generate 'watchdog NMI interrupts'. (NMI: Non Maskable Interrupt
which get executed even if the system is otherwise locked up hard).
This can be used to debug hard kernel lockups. By executing periodic
@@ -20,6 +22,13 @@
kernel debugging options such as Kernel Stack Meter or Kernel Tracer
may implicitly disable NMI watchdog.]
+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.)
+
To actually enable the NMI watchdog, use the 'nmi_watchdog=N' boot
parameter. Eg. the relevant lilo.conf entry:
next prev parent reply other threads:[~2003-07-28 19:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-23 17:43 [PATCH] NMI watchdog documentation Ville Herva
2003-07-28 17:53 ` Andi Kleen
2003-07-28 19:21 ` Ville Herva [this message]
2003-07-29 10:37 Mikael Pettersson
2003-07-29 16:06 ` Andi Kleen
2003-07-29 17:53 ` Ville Herva
2003-07-30 19:18 Mikael Pettersson
2003-07-30 19:20 Mikael Pettersson
2003-07-30 19:40 ` Ville Herva
2003-07-30 22:53 Mikael Pettersson
2003-07-31 5:44 ` Ville Herva
2003-07-31 21:25 Mikael Pettersson
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