path: root/Documentation/RCU/torture.txt
diff options
Diffstat (limited to 'Documentation/RCU/torture.txt')
1 files changed, 30 insertions, 3 deletions
diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
index d67068d..375d3fb 100644
--- a/Documentation/RCU/torture.txt
+++ b/Documentation/RCU/torture.txt
@@ -69,6 +69,13 @@ onoff_interval
CPU-hotplug operations regardless of what value is
specified for onoff_interval.
+onoff_holdoff The number of seconds to wait until starting CPU-hotplug
+ operations. This would normally only be used when
+ rcutorture was built into the kernel and started
+ automatically at boot time, in which case it is useful
+ in order to avoid confusing boot-time code with CPUs
+ coming and going.
The number of seconds to keep the test threads affinitied
to a particular subset of the CPUs, defaults to 3 seconds.
@@ -79,6 +86,24 @@ shutdown_secs The number of seconds to run the test before terminating
zero, which disables test termination and system shutdown.
This capability is useful for automated testing.
+stall_cpu The number of seconds that a CPU should be stalled while
+ within both an rcu_read_lock() and a preempt_disable().
+ This stall happens only once per rcutorture run.
+ If you need multiple stalls, use modprobe and rmmod to
+ repeatedly run rcutorture. The default for stall_cpu
+ is zero, which prevents rcutorture from stalling a CPU.
+ Note that attempts to rmmod rcutorture while the stall
+ is ongoing will hang, so be careful what value you
+ choose for this module parameter! In addition, too-large
+ values for stall_cpu might well induce failures and
+ warnings in other parts of the kernel. You have been
+ warned!
+ The number of seconds to wait after rcutorture starts
+ before stalling a CPU. Defaults to 10 seconds.
stat_interval The number of seconds between output of torture
statistics (via printk()). Regardless of the interval,
statistics are printed when the module is unloaded.
@@ -271,11 +296,13 @@ The following script may be used to torture RCU:
modprobe rcutorture
- sleep 100
+ sleep 3600
rmmod rcutorture
dmesg | grep torture:
The output can be manually inspected for the error flag of "!!!".
One could of course create a more elaborate script that automatically
-checked for such errors. The "rmmod" command forces a "SUCCESS" or
-"FAILURE" indication to be printk()ed.
+checked for such errors. The "rmmod" command forces a "SUCCESS",
+"FAILURE", or "RCU_HOTPLUG" indication to be printk()ed. The first
+two are self-explanatory, while the last indicates that while there
+were no RCU failures, CPU-hotplug problems were detected.