@@ -398,9 +398,9 @@ In kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y or booted with
rcupdate.rcu_cpu_stall_cputime=1, the following additional information
is supplied with each RCU CPU stall warning::
-rcu: hardirqs softirqs csw/system
-rcu: number: 624 45 0
-rcu: cputime: 69 1 2425 ==> 2500(ms)
+ rcu: hardirqs softirqs csw/system
+ rcu: number: 624 45 0
+ rcu: cputime: 69 1 2425 ==> 2500(ms)
These statistics are collected during the sampling period. The values
in row "number:" are the number of hard interrupts, number of soft
@@ -412,22 +412,24 @@ in milliseconds. Because user-mode tasks normally do not cause RCU CPU
stalls, these tasks are typically kernel tasks, which is why only the
system CPU time are considered.
-The sampling period is shown as follows:
-:<------------first timeout---------->:<-----second timeout----->:
-:<--half timeout-->:<--half timeout-->: :
-: :<--first period-->: :
-: :<-----------second sampling period---------->:
-: : : :
-: snapshot time point 1st-stall 2nd-stall
+The sampling period is shown as follows::
+ |<------------first timeout---------->|<-----second timeout----->|
+ |<--half timeout-->|<--half timeout-->| |
+ | |<--first period-->| |
+ | |<-----------second sampling period---------->|
+ | | | |
+ snapshot time point 1st-stall 2nd-stall
The following describes four typical scenarios:
-1. A CPU looping with interrupts disabled.::
+1. A CPU looping with interrupts disabled.
- rcu: hardirqs softirqs csw/system
- rcu: number: 0 0 0
- rcu: cputime: 0 0 0 ==> 2500(ms)
+ ::
+
+ rcu: hardirqs softirqs csw/system
+ rcu: number: 0 0 0
+ rcu: cputime: 0 0 0 ==> 2500(ms)
Because interrupts have been disabled throughout the measurement
interval, there are no interrupts and no context switches.
@@ -440,11 +442,11 @@ The following describes four typical scenarios:
This is similar to the previous example, but with non-zero number of
and CPU time consumed by hard interrupts, along with non-zero CPU
- time consumed by in-kernel execution.::
+ time consumed by in-kernel execution::
- rcu: hardirqs softirqs csw/system
- rcu: number: 624 0 0
- rcu: cputime: 49 0 2446 ==> 2500(ms)
+ rcu: hardirqs softirqs csw/system
+ rcu: number: 624 0 0
+ rcu: cputime: 49 0 2446 ==> 2500(ms)
The fact that there are zero softirqs gives a hint that these were
disabled, perhaps via local_bh_disable(). It is of course possible
@@ -454,20 +456,22 @@ The following describes four typical scenarios:
3. A CPU looping with preemption disabled.
- Here, only the number of context switches is zero.::
+ Here, only the number of context switches is zero::
- rcu: hardirqs softirqs csw/system
- rcu: number: 624 45 0
- rcu: cputime: 69 1 2425 ==> 2500(ms)
+ rcu: hardirqs softirqs csw/system
+ rcu: number: 624 45 0
+ rcu: cputime: 69 1 2425 ==> 2500(ms)
This situation hints that the stalled CPU was looping with preemption
disabled.
-4. No looping, but massive hard and soft interrupts.::
+4. No looping, but massive hard and soft interrupts.
+
+ ::
- rcu: hardirqs softirqs csw/system
- rcu: number: xx xx 0
- rcu: cputime: xx xx 0 ==> 2500(ms)
+ rcu: hardirqs softirqs csw/system
+ rcu: number: xx xx 0
+ rcu: cputime: xx xx 0 ==> 2500(ms)
Here, the number and CPU time of hard interrupts are all non-zero,
but the number of context switches and the in-kernel CPU time consumed