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

    * Paul E. McKenney <> 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.


    commit 5af970a48f3ba0dd96a036b196c79dc923f28231
    Author: Ingo Molnar <>
    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], "!!! ");
    + WARN_ON_ONCE(1);
    cnt += sprintf(&page[cnt], "Reader Pipe: ");
    for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)

     \ /
      Last update: 2008-06-18 15:15    [W:0.023 / U:4.092 seconds]
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