nmi_watchdog: update procfs nmi_watchdog file documentation

This patch updates the /proc/sys/kernel/nmi_watchdog documentation.

---
 Documentation/filesystems/proc.txt |   13 ++++++++-----
 Documentation/nmi_watchdog.txt     |    5 +++++
 2 files changed, 13 insertions(+), 5 deletions(-)

@@ -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
+in boot time.
+
 NOTE: In kernels prior to 2.4.2-ac18 the NMI-oopser is enabled unconditionally
 on x86 SMP boxes.
 

@@ -1336,12 +1336,15 @@ panic controls already in that directory
 nmi_watchdog
 ------------
 
-Enables/Disables the NMI watchdog on x86 systems.  When the value is non-zero
+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.
-
-Because the NMI watchdog shares registers with oprofile, by disabling the NMI
-watchdog, oprofile may have more registers to utilize.
+determine whether or not they are still functioning properly. Currently,
+passing "nmi_watchdog=" parameter in boot time is required for this function
+to work.
+
+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
 ------

[Aristeu Rozanski - Thu, Oct 30, 2008 at 11:17:14AM -0400]

| This patch updates the /proc/sys/kernel/nmi_watchdog documentation.
| 
| Signed-off-by: Aristeu Rozanski <[email protected]>
| 
| ---
|  Documentation/filesystems/proc.txt |   13 ++++++++-----
|  Documentation/nmi_watchdog.txt     |    5 +++++
|  2 files changed, 13 insertions(+), 5 deletions(-)
| 
| --- linus-2.6.orig/Documentation/nmi_watchdog.txt	2008-10-24 11:41:30.000000000 -0400
| +++ linus-2.6/Documentation/nmi_watchdog.txt	2008-10-29 16:38:12.000000000 -0400
| @@ -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
| +in boot time.
| +
|  NOTE: In kernels prior to 2.4.2-ac18 the NMI-oopser is enabled unconditionally
|  on x86 SMP boxes.
|  
| --- linus-2.6.orig/Documentation/filesystems/proc.txt	2008-10-24 11:41:28.000000000 -0400
| +++ linus-2.6/Documentation/filesystems/proc.txt	2008-10-30 11:16:36.000000000 -0400
| @@ -1336,12 +1336,15 @@ panic controls already in that directory
|  nmi_watchdog
|  ------------
|  
| -Enables/Disables the NMI watchdog on x86 systems.  When the value is non-zero
| +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.
| -
| -Because the NMI watchdog shares registers with oprofile, by disabling the NMI
| -watchdog, oprofile may have more registers to utilize.
| +determine whether or not they are still functioning properly. Currently,
| +passing "nmi_watchdog=" parameter in boot time is required for this function
| +to work.
| +
| +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
|  ------
| 

Hi Aristeu,

by reading this patch I found that maybe it's time to start using nmi_watchdog=[lapic,ioapic] instead of 1 and 2? We could make them as alases to existing numbers. Thoughts?

- Cyrill -

Yes, that would be useful.

Aristeu

[Aristeu Rozanski - Thu, Oct 30, 2008 at 11:51:21AM -0400]

| > Hi Aristeu,
| > 
| > by reading this patch I found that maybe it's time to start
| > using nmi_watchdog=[lapic,ioapic] instead of 1 and 2? We could make
| > them as alases to existing numbers. Thoughts?
| Yes, that would be useful.
| 
| -- 
| Aristeu
| 

ok, will handle it :)

- Cyrill -

This patch updates the /proc/sys/kernel/nmi_watchdog documentation.
Updated: included Randy Dunlap's corrections.

---
 Documentation/filesystems/proc.txt |   11 +++++++----
 Documentation/nmi_watchdog.txt     |    5 +++++
 2 files changed, 12 insertions(+), 4 deletions(-)

@@ -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.
 

@@ -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.
-
-Because the NMI watchdog shares registers with oprofile, by disabling the NMI
-watchdog, oprofile may have more registers to utilize.
+determine whether or not they are still functioning properly. Currently,
+passing "nmi_watchdog=" parameter at boot time is required for this function
+to work.
+
+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
 ------

applied to tip/x86/nmi-watchdog, thanks guys!

Ingo