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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-12-14 07:32:04 +0300
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-01-16 10:33:14 +0300
commit5cd37193ce8539be1e6ef76be226f4bcc984e0f5 (patch)
tree7bba4e3fd57b669d60e37fd32011db4860016505 /include/linux/rcupdate.h
parenta94844b22a2e2b9155bbc0878c507850477221c2 (diff)
downloadlinux-5cd37193ce8539be1e6ef76be226f4bcc984e0f5.tar.xz
rcu: Make cond_resched_rcu_qs() apply to normal RCU flavors
Although cond_resched_rcu_qs() only applies to TASKS_RCU, it is used in places where it would be useful for it to apply to the normal RCU flavors, rcu_preempt, rcu_sched, and rcu_bh. This is especially the case for workloads that aggressively overload the system, particularly those that generate large numbers of RCU updates on systems running NO_HZ_FULL CPUs. This commit therefore communicates quiescent states from cond_resched_rcu_qs() to the normal RCU flavors. Note that it is unfortunately necessary to leave the old ->passed_quiesce mechanism in place to allow quiescent states that apply to only one flavor to be recorded. (Yes, we could decrement ->rcu_qs_ctr_snap in that case, but that is not so good for debugging of RCU internals.) In addition, if one of the RCU flavor's grace period has stalled, this will invoke rcu_momentary_dyntick_idle(), resulting in a heavy-weight quiescent state visible from other CPUs. Reported-by: Sasha Levin <sasha.levin@oracle.com> Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Merge commit from Sasha Levin fixing a bug where __this_cpu() was used in preemptible code. ]
Diffstat (limited to 'include/linux/rcupdate.h')
-rw-r--r--include/linux/rcupdate.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index ed4f5939a452..468228750299 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -331,12 +331,13 @@ static inline void rcu_init_nohz(void)
extern struct srcu_struct tasks_rcu_exit_srcu;
#define rcu_note_voluntary_context_switch(t) \
do { \
+ rcu_all_qs(); \
if (ACCESS_ONCE((t)->rcu_tasks_holdout)) \
ACCESS_ONCE((t)->rcu_tasks_holdout) = false; \
} while (0)
#else /* #ifdef CONFIG_TASKS_RCU */
#define TASKS_RCU(x) do { } while (0)
-#define rcu_note_voluntary_context_switch(t) do { } while (0)
+#define rcu_note_voluntary_context_switch(t) rcu_all_qs()
#endif /* #else #ifdef CONFIG_TASKS_RCU */
/**