From 9577df9a3122af08fff84b8a1a60dccf524a3891 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 26 Jan 2017 16:18:07 -0800 Subject: rcu: Pull rcu_qs_ctr into rcu_dynticks structure The rcu_qs_ctr variable is yet another isolated per-CPU variable, so this commit pulls it into the pre-existing rcu_dynticks per-CPU structure. Signed-off-by: Paul E. McKenney --- .../RCU/Design/Data-Structures/Data-Structures.html | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'Documentation/RCU/Design/Data-Structures/Data-Structures.html') diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html index bf7f266e8888..3d0311657533 100644 --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html @@ -1105,6 +1105,7 @@ Its fields are as follows: 2 int dynticks_nmi_nesting; 3 atomic_t dynticks; 4 int rcu_sched_qs_mask; + 5 unsigned long rcu_qs_ctr;

The ->dynticks_nesting field counts the @@ -1123,12 +1124,19 @@ CPU's transitions to and from dyntick-idle mode, so that this counter has an even value when the CPU is in dyntick-idle mode and an odd value otherwise. -

Finally, the ->rcu_sched_qs_mask field is used +

The ->rcu_sched_qs_mask field is used to record the fact that the RCU core code would really like to -see a quiescent state from the corresponding CPU. +see a quiescent state from the corresponding CPU, so much so that +it is willing to call for heavy-weight dyntick-counter operations. This flag is checked by RCU's context-switch and cond_resched() code, which provide a momentary idle sojourn in response. +

Finally the ->rcu_qs_ctr field is used to record +quiescent states from cond_resched(). +Because cond_resched() can execute quite frequently, this +must be quite lightweight, as in a non-atomic increment of this +per-CPU field. + -- cgit
 
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