Lines Matching full:rcu
4 Using RCU's CPU Stall Detector
7 This document first discusses what sorts of issues RCU's CPU stall
13 What Causes RCU CPU Stall Warnings?
16 So your kernel printed an RCU CPU stall warning. The next question is
17 "What caused it?" The following problems can result in RCU CPU stall
20 - A CPU looping in an RCU read-side critical section.
37 RCU CPU stall warning messages. Especially if you have added
40 - Anything that prevents RCU's grace-period kthreads from running.
48 happen to preempt a low-priority task in the middle of an RCU
51 in which case the next RCU grace period can never complete, which
57 is running at a higher priority than the RCU softirq threads.
58 This will prevent RCU callbacks from ever being invoked,
60 RCU grace periods from ever completing. Either way, the
66 increase the scheduling priority of RCU's kthreads, which can
73 prevent RCU's kthreads and softirq handlers from running.
77 RCU CPU stall warnings.
80 timeout down to just barely avoid RCU CPU stall warnings, and then
88 result in RCU CPU stall warnings for CONFIG_NO_HZ_COMMON=n kernels.
95 yes, even including bugs in RCU itself. It can also result in
109 - A bug in the RCU implementation.
114 This resulted in a series of RCU CPU stall warnings, eventually
117 The RCU, RCU-sched, and RCU-tasks implementations have CPU stall warning.
119 RCU only detects CPU stalls when there is a grace period in progress.
130 RCU bugs can often be debugged with the help of CONFIG_RCU_TRACE
131 and with RCU's event tracing. For information on RCU's event tracing,
132 see include/trace/events/rcu.h.
135 Fine-Tuning the RCU CPU Stall Detector
138 The rcuupdate.rcu_cpu_stall_suppress module parameter disables RCU's
139 CPU stall detector, which detects conditions that unduly delay RCU grace
149 that RCU will wait from the beginning of a grace period until it
150 issues an RCU CPU stall warning. This time period is normally
170 of time that RCU will wait from the beginning of an expedited
171 grace period until it issues an RCU CPU stall warning. This time
191 giving an RCU CPU stall warning message. (This is a cpp
208 This boot/sysfs parameter controls the RCU-tasks stall warning
209 interval. A value of zero or less suppresses RCU-tasks stall
211 in seconds. An RCU-tasks stall warning starts with the line:
216 task stalling the current RCU-tasks grace period.
219 Interpreting RCU's CPU Stall-Detector "Splats"
222 For non-RCU-tasks flavors of RCU, when a CPU detects that some other
231 causing stalls, and that the stall was affecting RCU-sched. This message
241 the RCU core for the past three grace periods. In contrast, CPU 16's "(0
253 The "softirq=" portion of the message tracks the number of RCU softirq
261 across repeated stall-warning messages, it is possible that RCU's softirq
264 kernels, if a high-priority process is starving RCU's softirq handler.
274 an estimate of the total number of RCU callbacks queued across all CPUs
311 in RCU CPU stall warnings even when all CPUs and tasks have passed
335 change on successive RCU CPU stall warnings, there is further reason to