From: Paul E. McKenney Date: Wed, 12 Mar 2014 17:26:35 +0000 (-0700) Subject: rcutorture: Make rcu_torture_reader() use cond_resched() X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=64e4b43ae050146fcfafe696e61efc306f73d449;p=linux-beck.git rcutorture: Make rcu_torture_reader() use cond_resched() The rcu_torture_reader() function currently uses schedule(). This commit therefore speeds things up a bit by substituting cond_resched(). This change makes rcu_torture_reader() more CPU-bound, so this commit also adjusts the number of readers (the "nreaders" module parameter, which feeds into the "nrealreaders" variable) to allow one CPU to be free of readers on SMP systems. The point of this is to increase the probability that readers will be watching while an updater makes a change. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 37ae5e1d4a1d..693a90fcee83 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -942,7 +942,7 @@ rcu_torture_reader(void *arg) __this_cpu_inc(rcu_torture_batch[completed]); preempt_enable(); cur_ops->readunlock(idx); - schedule(); + cond_resched(); stutter_wait("rcu_torture_reader"); } while (!torture_must_stop()); if (irqreader && cur_ops->irq_capable) @@ -1482,10 +1482,13 @@ rcu_torture_init(void) if (cur_ops->init) cur_ops->init(); /* no "goto unwind" prior to this point!!! */ - if (nreaders >= 0) + if (nreaders >= 0) { nrealreaders = nreaders; - else - nrealreaders = 2 * num_online_cpus(); + } else { + nrealreaders = num_online_cpus() - 1; + if (nrealreaders <= 0) + nrealreaders = 1; + } rcu_torture_print_module_parms(cur_ops, "Start of test"); /* Set up the freelist. */