path: root/kernel/rcutree.h
diff options
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-07-21 08:05:56 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-08-19 17:18:04 -0700
commit910b1b7e19a292ff685001caf1bf1a9775b771a1 (patch)
tree7ec42bf018ab62c3c2180fbe168cd6130556cb80 /kernel/rcutree.h
parent687d7a960aea46e016182c7ce346d62c4dbd0366 (diff)
rcu: Allow RCU CPU stall warnings to be off at boot, but manually enablable
Currently, if RCU CPU stall warnings are enabled, they are enabled immediately upon boot. They can be manually disabled via /sys (and also re-enabled via /sys), and are automatically disabled upon panic. However, some users need RCU CPU stalls to be disabled at boot time, but to be enabled without rebuilding/rebooting. For example, someone running a real-time application in production might not want the additional latency of RCU CPU stall detection in normal operation, but might need to enable it at any point for fault isolation purposes. This commit therefore provides a new CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE kernel configuration parameter that maintains the current behavior (enable at boot) by default, but allows a kernel to be configured with RCU CPU stall detection built into the kernel, but disabled at boot time. Requested-by: Clark Williams <williams@redhat.com> Requested-by: John Kacur <jkacur@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.h')
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 183ebf405315..bb4d08695c45 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -264,6 +264,12 @@ struct rcu_data {
/* scheduling clock irq */
/* before ratting on them. */
#define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b))

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