From 8a1c8eb75be492e20003966652c9cd5ff57a559d Mon Sep 17 00:00:00 2001 From: Aristeu Rozanski <aris@redhat.com> Date: Thu, 30 Oct 2008 13:08:50 -0400 Subject: [PATCH] x86, nmi-watchdog: update procfs nmi_watchdog file documentation v2 Impact: improve documentation This patch updates the /proc/sys/kernel/nmi_watchdog documentation. Updated: included Randy Dunlap's corrections. Signed-off-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- Documentation/filesystems/proc.txt | 9 ++++++--- Documentation/nmi_watchdog.txt | 5 +++++ 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index bcceb99b81dd..86be879ed70e 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1338,10 +1338,13 @@ nmi_watchdog Enables/Disables the NMI watchdog on x86 systems. When the value is non-zero the NMI watchdog is enabled and will continuously test all online cpus to -determine whether or not they are still functioning properly. +determine whether or not they are still functioning properly. Currently, +passing "nmi_watchdog=" parameter at boot time is required for this function +to work. -Because the NMI watchdog shares registers with oprofile, by disabling the NMI -watchdog, oprofile may have more registers to utilize. +If LAPIC NMI watchdog method is in use (nmi_watchdog=2 kernel parameter), the +NMI watchdog shares registers with oprofile. By disabling the NMI watchdog, +oprofile may have more registers to utilize. msgmni ------ diff --git a/Documentation/nmi_watchdog.txt b/Documentation/nmi_watchdog.txt index 90aa4531cb67..bf9f80a98282 100644 --- a/Documentation/nmi_watchdog.txt +++ b/Documentation/nmi_watchdog.txt @@ -69,6 +69,11 @@ to the overall system performance. On x86 nmi_watchdog is disabled by default so you have to enable it with a boot time parameter. +It's possible to disable the NMI watchdog in run-time by writing "0" to +/proc/sys/kernel/nmi_watchdog. Writing "1" to the same file will re-enable +the NMI watchdog. Notice that you still need to use "nmi_watchdog=" parameter +at boot time. + NOTE: In kernels prior to 2.4.2-ac18 the NMI-oopser is enabled unconditionally on x86 SMP boxes. -- GitLab