From 64e4b43ae050146fcfafe696e61efc306f73d449 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 12 Mar 2014 10:26:35 -0700 Subject: [PATCH] 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 --- kernel/rcu/rcutorture.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 37ae5e1..693a90f 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. */ -- 2.7.4