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authorPaul E. McKenney <paulmck@kernel.org>2020-12-19 18:34:35 +0300
committerPaul E. McKenney <paulmck@kernel.org>2021-01-07 04:17:22 +0300
commit1afb95fee0342b8d9e05b0433e8e44a6dfd7c4a3 (patch)
tree914c500a93b70e478801a69c2018192dde0388f1 /include/linux/torture.h
parent0b962c8fe0e5c72a252b236814a6b6e9df799061 (diff)
downloadlinux-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 'include/linux/torture.h')
-rw-r--r--include/linux/torture.h5
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);