[PATCH for review] [14/145] x86_64: Add abilty to enable/disable nmi watchdog from procfs (update)

Andi Kleen
2006-08-10T20:14:32Z

r

From: Don Zickus <dzickus@redhat.com>

Adds a new /proc/sys/kernel/nmi_watchdog call that will enable/disable the
nmi watchdog.

By entering a non-zero value here, a user can enable the nmi watchdog to
monitor the online cpus in the system. By entering a zero value here, a
user can disable the nmi watchdog and free up a performance counter which
could then be utilized by the oprofile subsystem, otherwise oprofile may be
short a counter when in use.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

Documentation/filesystems/proc.txt | 14 +++++++++-----
arch/i386/kernel/nmi.c | 21 ++++-----------------
arch/x86_64/kernel/nmi.c | 21 ++++-----------------
3 files changed, 17 insertions(+), 39 deletions(-)

Index: linux/arch/i386/kernel/nmi.c
===================================================================
--- linux.orig/arch/i386/kernel/nmi.c
+++ linux/arch/i386/kernel/nmi.c
@@ -847,7 +847,7 @@ static int unknown_nmi_panic_callback(st
}

/*
- * proc handler for /proc/sys/kernel/nmi_watchdog
+ * proc handler for /proc/sys/kernel/nmi
*/
int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
void __user *buffer, size_t *length, loff_t *ppos)
@@ -861,8 +861,8 @@ int proc_nmi_enabled(struct ctl_table *t
return 0;

if (atomic_read(&nmi_active) < 0) {
- printk(KERN_WARNING "NMI watchdog is permanently disabled\n");
- return -EINVAL;
+ printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
+ return -EIO;
}

if (nmi_watchdog == NMI_DEFAULT) {
@@ -872,24 +872,11 @@ int proc_nmi_enabled(struct ctl_table *t
nmi_watchdog = NMI_IO_APIC;
}

- if (nmi_watchdog == NMI_LOCAL_APIC)
- {
+ if (nmi_watchdog == NMI_LOCAL_APIC) {
if (nmi_watchdog_enabled)
enable_lapic_nmi_watchdog();
else
disable_lapic_nmi_watchdog();
- } else if (nmi_watchdog == NMI_IO_APIC) {
- /* FIXME
- * for some reason these functions don't work
- */
- printk("Can not enable/disable NMI on IO APIC\n");
- return -EINVAL;
-#if 0
- if (nmi_watchdog_enabled)
- enable_timer_nmi_watchdog();
- else
- disable_timer_nmi_watchdog();
-#endif
} else {
printk( KERN_WARNING
"NMI watchdog doesn't know what hardware to touch\n");
Index: linux/arch/x86_64/kernel/nmi.c
===================================================================
--- linux.orig/arch/x86_64/kernel/nmi.c
+++ linux/arch/x86_64/kernel/nmi.c
@@ -167,7 +167,7 @@ static __cpuinit inline int nmi_known_cp
}

/* Run after command line and cpu_init init, but before all other checks */
-void __cpuinit nmi_watchdog_default(void)
+void nmi_watchdog_default(void)
{
if (nmi_watchdog != NMI_DEFAULT)
return;
@@ -766,32 +766,19 @@ int proc_nmi_enabled(struct ctl_table *t

if (atomic_read(&nmi_active) < 0) {
printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
- return -EINVAL;
+ return -EIO;
}

/* if nmi_watchdog is not set yet, then set it */
nmi_watchdog_default();

- if (nmi_watchdog == NMI_LOCAL_APIC)
- {
+ if (nmi_watchdog == NMI_LOCAL_APIC) {
if (nmi_watchdog_enabled)
enable_lapic_nmi_watchdog();
else
disable_lapic_nmi_watchdog();
- } else if (nmi_watchdog == NMI_IO_APIC) {
- /* FIXME
- * for some reason these functions don't work
- */
- printk("Can not enable/disable NMI on IO APIC\n");
- return -EIO;
-#if 0
- if (nmi_watchdog_enabled)
- enable_timer_nmi_watchdog();
- else
- disable_timer_nmi_watchdog();
-#endif
} else {
- printk(KERN_WARNING
+ printk( KERN_WARNING
"NMI watchdog doesn't know what hardware to touch\n");
return -EIO;
}
Index: linux/Documentation/filesystems/proc.txt
===================================================================
--- linux.orig/Documentation/filesystems/proc.txt
+++ linux/Documentation/filesystems/proc.txt
@@ -1124,11 +1124,15 @@ debugging information is displayed on co
NMI switch that most IA32 servers have fires unknown NMI up, for example.
If a system hangs up, try pressing the NMI switch.

-[NOTE]
- This function and oprofile share a NMI callback. Therefore this function
- cannot be enabled when oprofile is activated.
- And NMI watchdog will be disabled when the value in this file is set to
- non-zero.
+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.

2.4 /proc/sys/vm - The virtual memory subsystem