Lines Matching refs:stall
7 This document first discusses what sorts of issues RCU's CPU stall
10 this document explains the stall detector's "splat" format.
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
37 RCU CPU stall warning messages. Especially if you have added
54 memory, you might see stall-warning messages.
62 CONFIG_PREEMPT_RCU case, you might see stall-warning
77 RCU CPU stall warnings.
79 - Testing a workload on a fast system, tuning the stall-warning
80 timeout down to just barely avoid RCU CPU stall warnings, and then
81 running the same workload with the same stall-warning timeout on a
88 result in RCU CPU stall warnings for CONFIG_NO_HZ_COMMON=n kernels.
115 of RCU CPU stall warnings, eventually leading the realization
119 CPU stall warning. Note that SRCU does *not* have CPU stall warnings.
121 in progress. No grace period, no CPU stall warnings.
123 To diagnose the cause of the stall, inspect the stack traces.
125 If you have a series of stall warnings from a single extended stall,
126 comparing the stack traces can often help determine where the stall
129 If you can reliably trigger the stall, ftrace can be quite helpful.
140 CPU stall detector, which detects conditions that unduly delay RCU grace
141 periods. This module parameter enables CPU stall detection by default,
143 The stall detector's idea of what constitutes "unduly delayed" is
151 issues an RCU CPU stall warning. This time period is normally
157 So if you are 10 seconds into a 40-second stall, setting this
159 *next* stall, or the following warning for the current stall
160 (assuming the stall lasts long enough). It will not affect the
161 timing of the next warning for the current stall.
172 grace period until it issues an RCU CPU stall warning. This time
180 are in a current stall cycle, setting it to a new value will change
181 the timeout for the -next- stall.
192 giving an RCU CPU stall warning message. (This is a cpp
198 The CPU stall detector tries to make the offending CPU print its
200 However, if the offending CPU does not detect its own stall in
210 RCU-tasks-trace stall warning intervals. A value of zero or less
211 suppresses RCU-tasks stall warnings. A positive value sets the
212 stall-warning interval in seconds. An RCU-tasks stall warning
220 An RCU-tasks-trace stall warning starts (and continues) similarly:
237 causing stalls, and that the stall was affecting RCU-sched. This message
241 possible for an rcu_state stall to be caused by both CPUs *and* tasks,
244 in a self-detected stall.
268 across repeated stall-warning messages, it is possible that RCU's softirq
278 The "detected by" line indicates which CPU detected the stall (in this
284 If the grace period ends just as the stall warning starts printing,
285 there will be a spurious stall-warning message, which will include
291 possible for a zero-jiffy stall to be flagged in this case, depending
292 on how the stall warning and the grace-period initialization happen to
298 grace period has nevertheless failed to end, the stall-warning splat
311 the stall warning, as was the case in the "All QSes seen" line above,
318 in RCU CPU stall warnings even when all CPUs and tasks have passed
342 change on successive RCU CPU stall warnings, there is further reason to
346 involved in the stall. These stack traces can help you locate the cause
347 of the stall, keeping in mind that the CPU detecting the stall will have
348 an interrupt frame that is mainly devoted to detecting the stall.
354 If a stall lasts long enough, multiple stall-warning messages will
358 of the stall and the first message. It can be helpful to compare the
365 If an expedited grace period detects a stall, it will place a message
391 It is entirely possible to see stall warnings from normal and from
399 is supplied with each RCU CPU stall warning::
422 snapshot time point 1st-stall 2nd-stall
482 If this type of RCU CPU stall warning can be reproduced, you can