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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-01-27 13:17:02 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-04-18 11:38:18 -0700
commit0f9be8cabbc343218dd2807af7308656be113045 (patch)
treed99e786bc49f6d77bbd1fa4fa7c4df31de9fed8d /Documentation/RCU
parent9577df9a3122af08fff84b8a1a60dccf524a3891 (diff)
rcu: Eliminate flavor scan in rcu_momentary_dyntick_idle()
The rcu_momentary_dyntick_idle() function scans the RCU flavors, checking that one of them still needs a quiescent state before doing an expensive atomic operation on the ->dynticks counter. However, this check reduces overhead only after a rare race condition, and increases complexity. This commit therefore removes the scan and the mechanism enabling the scan. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/Design/Data-Structures/Data-Structures.html4
1 files changed, 2 insertions, 2 deletions
diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html
index 3d0311657533..e4bf20a68fa3 100644
--- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html
+++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html
@@ -1104,7 +1104,7 @@ Its fields are as follows:
1 int dynticks_nesting;
2 int dynticks_nmi_nesting;
3 atomic_t dynticks;
- 4 int rcu_sched_qs_mask;
+ 4 bool rcu_need_heavy_qs;
5 unsigned long rcu_qs_ctr;
</pre>
@@ -1124,7 +1124,7 @@ 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>The <tt>-&gt;rcu_sched_qs_mask</tt> field is used
+</p><p>The <tt>-&gt;rcu_need_heavy_qs</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, so much so that
it is willing to call for heavy-weight dyntick-counter operations.