summaryrefslogtreecommitdiff
path: root/Documentation/RCU/Design/Data-Structures/Data-Structures.html
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/RCU/Design/Data-Structures/Data-Structures.html')
-rw-r--r--Documentation/RCU/Design/Data-Structures/Data-Structures.html12
1 files changed, 10 insertions, 2 deletions
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;
</pre>
<p>The <tt>-&gt;dynticks_nesting</tt> 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.
-</p><p>Finally, the <tt>-&gt;rcu_sched_qs_mask</tt> field is used
+</p><p>The <tt>-&gt;rcu_sched_qs_mask</tt> 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 <tt>cond_resched()</tt>
code, which provide a momentary idle sojourn in response.
+</p><p>Finally the <tt>-&gt;rcu_qs_ctr</tt> field is used to record
+quiescent states from <tt>cond_resched()</tt>.
+Because <tt>cond_resched()</tt> can execute quite frequently, this
+must be quite lightweight, as in a non-atomic increment of this
+per-CPU field.
+
<table>
<tr><th>&nbsp;</th></tr>
<tr><th align="left">Quick Quiz:</th></tr>