diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2020-12-19 07:34:35 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-01-06 17:17:22 -0800 |
| commit | 1afb95fee0342b8d9e05b0433e8e44a6dfd7c4a3 (patch) | |
| tree | 914c500a93b70e478801a69c2018192dde0388f1 /include/linux/torture.h | |
| parent | 0b962c8fe0e5c72a252b236814a6b6e9df799061 (diff) | |
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 'include/linux/torture.h')
| -rw-r--r-- | include/linux/torture.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/torture.h b/include/linux/torture.h index d62d13c8c69a..0910c5803f35 100644 --- a/include/linux/torture.h +++ b/include/linux/torture.h @@ -48,6 +48,11 @@ do { \ void verbose_torout_sleep(void); /* Definitions for online/offline exerciser. */ +#ifdef CONFIG_HOTPLUG_CPU +int torture_num_online_cpus(void); +#else /* #ifdef CONFIG_HOTPLUG_CPU */ +static inline int torture_num_online_cpus(void) { return 1; } +#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */ typedef void torture_ofl_func(void); bool torture_offline(int cpu, long *n_onl_attempts, long *n_onl_successes, unsigned long *sum_offl, int *min_onl, int *max_onl); |