lockup_detector: Combine nmi_watchdog and softlockup detector

[linux-2.6-block.git] / lib / Kconfig.debug

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 220ae6063b6f220dafba15d80c32deabc4453e37..49e285dcaf579d53e7ef68acebf3b03806b7e0a9 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -153,7 +153,7 @@ config DEBUG_SHIRQ
          points; some don't and need to be caught.
 
 config DETECT_SOFTLOCKUP
-       bool "Detect Soft Lockups"
+       bool
        depends on DEBUG_KERNEL && !S390
        default y
        help
@@ -171,17 +171,27 @@ config DETECT_SOFTLOCKUP
           can be detected via the NMI-watchdog, on platforms that
           support it.)
 
-config NMI_WATCHDOG
-       bool "Detect Hard Lockups with an NMI Watchdog"
-       depends on DEBUG_KERNEL && PERF_EVENTS && PERF_EVENTS_NMI
+config LOCKUP_DETECTOR
+       bool "Detect Hard and Soft Lockups"
+       depends on DEBUG_KERNEL
+       default DETECT_SOFTLOCKUP
        help
-         Say Y here to enable the kernel to use the NMI as a watchdog
-         to detect hard lockups.  This is useful when a cpu hangs for no
-         reason but can still respond to NMIs.  A backtrace is displayed
-         for reviewing and reporting.
+         Say Y here to enable the kernel to act as a watchdog to detect
+         hard and soft lockups.
+
+         Softlockups are bugs that cause the kernel to loop in kernel
+         mode for more than 60 seconds, without giving other tasks a
+         chance to run.  The current stack trace is displayed upon
+         detection and the system will stay locked up.
+
+         Hardlockups are bugs that cause the CPU to loop in kernel mode
+         for more than 60 seconds, without letting other interrupts have a
+         chance to run.  The current stack trace is displayed upon detection
+         and the system will stay locked up.
 
-         The overhead should be minimal, just an extra NMI every few
-         seconds.
+         The overhead should be minimal.  A periodic hrtimer runs to
+         generate interrupts and kick the watchdog task every 10-12 seconds.
+         An NMI is generated every 60 seconds or so to check for hardlockups.
 
 config BOOTPARAM_SOFTLOCKUP_PANIC
        bool "Panic (Reboot) On Soft Lockups"