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| author | Paul E. McKenney <paulmck@kernel.org> | 2020-12-19 18:34:35 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-01-07 04:17:22 +0300 |
| commit | 1afb95fee0342b8d9e05b0433e8e44a6dfd7c4a3 (patch) | |
| tree | 914c500a93b70e478801a69c2018192dde0388f1 /kernel/rcu | |
| parent | 0b962c8fe0e5c72a252b236814a6b6e9df799061 (diff) | |
| download | linux-1afb95fee0342b8d9e05b0433e8e44a6dfd7c4a3.tar.xz | |
torture: Maintain torture-specific set of CPUs-online books
The TREE01 rcutorture scenario intentionally creates confusion as to the
number of available CPUs by specifying the "maxcpus=8 nr_cpus=43" kernel
boot parameters. This can disable rcutorture's load shedding, which
currently uses num_online_cpus(), which would count the extra 35 CPUs.
However, the rcutorture guest OS will be provisioned with only 8 CPUs,
which means that rcutorture will present full load even when all but one
of the original 8 CPUs are offline. This can result in spurious errors
due to extreme overloading of that single remaining CPU.
This commit therefore keeps a separate set of books on the number of
usable online CPUs, so that torture_num_online_cpus() is used for load
shedding instead of num_online_cpus(). Note that initial sizing must
use num_online_cpus() because torture_num_online_cpus() will return
NR_CPUS until shortly after torture_onoff_init() is invoked.
Reported-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Apply feedback from kernel test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/rcutorture.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 76c838696366..a816df4e86e0 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1338,7 +1338,7 @@ static void rcu_torture_reader_do_mbchk(long myid, struct rcu_torture *rtp, struct torture_random_state *trsp) { unsigned long loops; - int noc = num_online_cpus(); + int noc = torture_num_online_cpus(); int rdrchked; int rdrchker; struct rcu_torture_reader_check *rtrcp; // Me. @@ -1658,7 +1658,7 @@ rcu_torture_reader(void *arg) torture_hrtimeout_us(500, 1000, &rand); lastsleep = jiffies + 10; } - while (num_online_cpus() < mynumonline && !torture_must_stop()) + while (torture_num_online_cpus() < mynumonline && !torture_must_stop()) schedule_timeout_interruptible(HZ / 5); stutter_wait("rcu_torture_reader"); } while (!torture_must_stop()); |