Messages in this thread | | | Date | Fri, 15 Jun 2012 14:52:48 -0700 | From | Josh Triplett <> | Subject | Re: [PATCH tip/core/rcu 6/6] rcu: Make rcutorture fakewriters invoke rcu_barrier() |
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On Fri, Jun 15, 2012 at 02:19:02PM -0700, Paul E. McKenney wrote: > On Fri, Jun 15, 2012 at 01:37:05PM -0700, Josh Triplett wrote: > > On Fri, Jun 15, 2012 at 11:57:54AM -0700, Paul E. McKenney wrote: > > > From: "Paul E. McKenney" <paul.mckenney@linaro.org> > > > > > > The current rcutorture rcu_barrier() testing never intentionally runs > > > more than one instance of rcu_barrier() at a given time. This fails > > > to test the the shiny new concurrency features of rcu_barrier(). This > > > commit therefore modifies the rcutorture fakewriter kthread to randomly > > > invoke rcu_barrier() rather than the usual synchronize_rcu(). > > > > > > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> > > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > --- > > > kernel/rcutorture.c | 6 +++++- > > > 1 files changed, 5 insertions(+), 1 deletions(-) > > > > > > diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c > > > index 54a3745..dfb4e20 100644 > > > --- a/kernel/rcutorture.c > > > +++ b/kernel/rcutorture.c > > > @@ -1025,7 +1025,11 @@ rcu_torture_fakewriter(void *arg) > > > do { > > > schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10); > > > udelay(rcu_random(&rand) & 0x3ff); > > > - cur_ops->sync(); > > > + if (cur_ops->cb_barrier != NULL && > > > + rcu_random(&rand) % (NR_CPUS * 8) == 0) > > > > NR_CPUS seems like an odd choice here. I assume you want to control for > > having many rcu_torture_fakewriter threads, and aim for the same average > > rate of barrier calls across the whole set of threads regardless of the > > number of threads. However, NR_CPUS does not accurately reflect either > > the number of fakewriter threads (which a user can set arbitrarily) or > > the number of CPUs currently on the system (since NR_CPUS represents the > > compile-time limit). I'd suggest changing this to use the actual number > > of fakewriter threads, which rcutorture knows at start time. > > Indeed, this should use the number of online CPUs. Which should be > easy to compute, will fix.
I'd suggest using nfakewriters instead.
- Josh Triplett
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