Messages in this thread | | | From | Joel Fernandes <> | Date | Wed, 7 Dec 2022 22:42:01 +0000 | Subject | Re: [PATCH RFC 2/3] locktorture: Allow non-rtmutex lock types to be boosted |
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On Wed, Dec 7, 2022 at 10:23 PM Joel Fernandes <joel@joelfernandes.org> wrote: > > Hi Paul, > > On Wed, Dec 7, 2022 at 10:14 PM Paul E. McKenney <paulmck@kernel.org> wrote: > > > > On Wed, Nov 23, 2022 at 01:21:03AM +0000, Joel Fernandes (Google) wrote: > > > Currently RT boosting is only done for rtmutex_lock, however with proxy > > > execution, we also have the mutex_lock participating in priorities. To > > > exercise the testing better, add RT boosting to other lock testing types > > > as well, using a new knob (rt_boost). > > > > > > Tested with boot parameters: > > > locktorture.torture_type=mutex_lock > > > locktorture.onoff_interval=1 > > > locktorture.nwriters_stress=8 > > > locktorture.stutter=0 > > > locktorture.rt_boost=1 > > > locktorture.rt_boost_factor=1 > > > locktorture.nlocks=3 > > > > > > For the rtmutex test, rt_boost is always enabled even if disabling is > > > requested. > > > > > > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > > > --- > > > kernel/locking/locktorture.c | 91 +++++++++++++++++++----------------- > > > 1 file changed, 48 insertions(+), 43 deletions(-) > > > > > > diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c > > > index bc3557677eed..5a388ac96a9b 100644 > > > --- a/kernel/locking/locktorture.c > > > +++ b/kernel/locking/locktorture.c > > > @@ -46,6 +46,7 @@ torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable."); > > > torture_param(int, stat_interval, 60, > > > "Number of seconds between stats printk()s"); > > > torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable"); > > > +torture_param(int, rt_boost, 0, "Perform an rt-boost from the writer, always 1 for rtmutex_lock"); > > > torture_param(int, verbose, 1, > > > "Enable verbose debugging printk()s"); > > > torture_param(int, nlocks, 1, > > > @@ -129,15 +130,44 @@ static void torture_lock_busted_write_unlock(int tid __maybe_unused) > > > /* BUGGY, do not use in real life!!! */ > > > } > > > > > > -static void torture_boost_dummy(struct torture_random_state *trsp) > > > > We no longer have torture_boot_dummy(). Is the point that the > > "spinlocks" to priority boosting in PREEMPT_RT kernels? If so, > > would it make sense to do something like this for spinlock? > > > > .task_boost = IS_ENABLED(CONFIG_PREEMPT_RT) ? torture_rt_boost : torture_boost_dummy, > > > > Or maybe using a similar approach for the default value of the rt_boost > > module parameter? > > > > Or is there some benefit of priority boosting for spinlocks even in > > non-PREEMPT_RT kernels that I am missing? > > There are 2 advantages as far as I can see: > > 1. The shuffle thread which ends up in setscheduler exercises the same > path as the rt mutex boost, so that would test races with that and the > boost path.
I was too hasty in my reply, I meant here the thread's "RT boost" racing with other paths such as migration / schedule() / other setscheduler() paths.
Obviously rtmutex boost does not happen when there is no rtmutex to begin with.
Thanks,
- Joel
> > > > > Thanx, Paul > > > > > .writelock = torture_rtmutex_lock, > > > .write_delay = torture_rtmutex_delay, > > > - .task_boost = torture_rtmutex_boost, > > > + .task_boost = torture_rt_boost, > > > .writeunlock = torture_rtmutex_unlock, > > > .readlock = NULL, > > > .read_delay = NULL, > > > @@ -604,7 +609,7 @@ __releases(torture_rwsem) > > > static struct lock_torture_ops rwsem_lock_ops = { > > > .writelock = torture_rwsem_down_write, > > > .write_delay = torture_rwsem_write_delay, > > > - .task_boost = torture_boost_dummy, > > > + .task_boost = torture_rt_boost, > > > .writeunlock = torture_rwsem_up_write, > > > .readlock = torture_rwsem_down_read, > > > .read_delay = torture_rwsem_read_delay, > > > @@ -656,7 +661,7 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = { > > > .exit = torture_percpu_rwsem_exit, > > > .writelock = torture_percpu_rwsem_down_write, > > > .write_delay = torture_rwsem_write_delay, > > > - .task_boost = torture_boost_dummy, > > > + .task_boost = torture_rt_boost, > > > .writeunlock = torture_percpu_rwsem_up_write, > > > .readlock = torture_percpu_rwsem_down_read, > > > .read_delay = torture_rwsem_read_delay, > > > -- > > > 2.38.1.584.g0f3c55d4c2-goog > > >
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