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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2008-10-02 16:06:39 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-10-03 10:36:08 +0200 |
| commit | 2133b5d7ff531bc15a923db4a6a50bf96c561be9 (patch) | |
| tree | 5917515eaec573fbc3d4a734769d6184beb83dbb /include/linux | |
| parent | b5259d944279d0b7e78a83849a352d8ba0447c4c (diff) | |
| download | blackbird-op-linux-2133b5d7ff531bc15a923db4a6a50bf96c561be9.tar.gz blackbird-op-linux-2133b5d7ff531bc15a923db4a6a50bf96c561be9.zip | |
rcu: RCU-based detection of stalled CPUs for Classic RCU
This patch adds stalled-CPU detection to Classic RCU. This capability
is enabled by a new config variable CONFIG_RCU_CPU_STALL_DETECTOR, which
defaults disabled.
This is a debugging feature to detect infinite loops in kernel code, not
something that non-kernel-hackers would be expected to care about.
This feature can detect looping CPUs in !PREEMPT builds and looping CPUs
with preemption disabled in PREEMPT builds. This is essentially a port of
this functionality from the treercu patch, replacing the stall debug patch
that is already in tip/core/rcu (commit 67182ae1c4).
The changes from the patch in tip/core/rcu include making the config
variable name match that in treercu, changing from seconds to jiffies to
avoid spurious warnings, and printing a boot message when this feature
is enabled.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/rcuclassic.h | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h index 29bf528c7dcc..5f89b62e6983 100644 --- a/include/linux/rcuclassic.h +++ b/include/linux/rcuclassic.h @@ -40,15 +40,21 @@ #include <linux/cpumask.h> #include <linux/seqlock.h> +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR +#define RCU_SECONDS_TILL_STALL_CHECK ( 3 * HZ) /* for rcp->jiffies_stall */ +#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ) /* for rcp->jiffies_stall */ +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ /* Global control variables for rcupdate callback mechanism. */ struct rcu_ctrlblk { long cur; /* Current batch number. */ long completed; /* Number of the last completed batch */ long pending; /* Number of the last pending batch */ -#ifdef CONFIG_DEBUG_RCU_STALL - unsigned long gp_check; /* Time grace period should end, in seconds. */ -#endif /* #ifdef CONFIG_DEBUG_RCU_STALL */ +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR + unsigned long gp_start; /* Time at which GP started in jiffies. */ + unsigned long jiffies_stall; + /* Time at which to check for CPU stalls. */ +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ int signaled; |
