Re: [PATCH] Make rcutorture more vicious: add stutter feature


* Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:

Hello!

This patch takes a step towards making rcutorture more brutal by
allowing the test to be automatically periodically paused, with the
default being to run the test for five seconds then pause for five
seconds and repeat. This behavior can be controlled using a new
"stutter" module parameter, so that "stutter=0" gives the old default
behavior of running continuously.

Starting and stopping rcutorture more heavily stresses RCU's
interaction with the scheduler, as well as exercising more paths
through the grace-period detection code.

cool! Applied to tip/core/rcu.

Note that the default to "shuffle_interval" has also been adjusted
from 5 seconds to 3 seconds to provide varying overlap with the
"stutter" interval.

I am still unable to provoke the failures that Alexey has been seeing,
even with this patch, but will be doing a few additional things to
beef up rcutorture.

neither am i able to see any rcu-preempt+rcu-torture failures in my
testing, despite having added the patch below to tip/core/rcu as well to
make any failures more apparent.

Ingo

------------------>
commit 5af970a48f3ba0dd96a036b196c79dc923f28231
Author: Ingo Molnar <mingo@xxxxxxx>
Date: Wed Jun 18 10:09:48 2008 +0200

rcutorture: WARN_ON_ONCE(1) when detecting an error

this makes it easier for automated tests to pick up such failures.

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 0334b6a..0ca7e9b 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -687,6 +687,7 @@ rcu_torture_printk(char *page)
if (i > 1) {
cnt += sprintf(&page[cnt], "!!! ");
atomic_inc(&n_rcu_torture_error);
+ WARN_ON_ONCE(1);
}
cnt += sprintf(&page[cnt], "Reader Pipe: ");
for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
--
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