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Diffstat (limited to 'Documentation/RCU/Design/Data-Structures/Data-Structures.html')
| -rw-r--r-- | Documentation/RCU/Design/Data-Structures/Data-Structures.html | 31 |
1 files changed, 12 insertions, 19 deletions
diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html index f5120a00f511..1d2051c0c3fc 100644 --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html @@ -1227,9 +1227,11 @@ to overflow the counter, this approach corrects the CPU enters the idle loop from process context. </p><p>The <tt>->dynticks</tt> field counts the corresponding -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. +CPU's transitions to and from either dyntick-idle or user mode, so +that this counter has an even value when the CPU is in dyntick-idle +mode or user mode and an odd value otherwise. The transitions to/from +user mode need to be counted for user mode adaptive-ticks support +(see timers/NO_HZ.txt). </p><p>The <tt>->rcu_need_heavy_qs</tt> field is used to record the fact that the RCU core code would really like to @@ -1372,8 +1374,7 @@ that is, if the CPU is currently idle. Accessor Functions</a></h3> <p>The following listing shows the -<tt>rcu_get_root()</tt>, <tt>rcu_for_each_node_breadth_first</tt>, -<tt>rcu_for_each_nonleaf_node_breadth_first()</tt>, and +<tt>rcu_get_root()</tt>, <tt>rcu_for_each_node_breadth_first</tt> and <tt>rcu_for_each_leaf_node()</tt> function and macros: <pre> @@ -1386,13 +1387,9 @@ Accessor Functions</a></h3> 7 for ((rnp) = &(rsp)->node[0]; \ 8 (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) 9 - 10 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ - 11 for ((rnp) = &(rsp)->node[0]; \ - 12 (rnp) < (rsp)->level[NUM_RCU_LVLS - 1]; (rnp)++) - 13 - 14 #define rcu_for_each_leaf_node(rsp, rnp) \ - 15 for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \ - 16 (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) + 10 #define rcu_for_each_leaf_node(rsp, rnp) \ + 11 for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \ + 12 (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++) </pre> <p>The <tt>rcu_get_root()</tt> simply returns a pointer to the @@ -1405,10 +1402,7 @@ macro takes advantage of the layout of the <tt>rcu_node</tt> structures in the <tt>rcu_state</tt> structure's <tt>->node[]</tt> array, performing a breadth-first traversal by simply traversing the array in order. -The <tt>rcu_for_each_nonleaf_node_breadth_first()</tt> macro operates -similarly, but traverses only the first part of the array, thus excluding -the leaf <tt>rcu_node</tt> structures. -Finally, the <tt>rcu_for_each_leaf_node()</tt> macro traverses only +Similarly, the <tt>rcu_for_each_leaf_node()</tt> macro traverses only the last part of the array, thus traversing only the leaf <tt>rcu_node</tt> structures. @@ -1416,15 +1410,14 @@ the last part of the array, thus traversing only the leaf <tr><th> </th></tr> <tr><th align="left">Quick Quiz:</th></tr> <tr><td> - What do <tt>rcu_for_each_nonleaf_node_breadth_first()</tt> and + What does <tt>rcu_for_each_leaf_node()</tt> do if the <tt>rcu_node</tt> tree contains only a single node? </td></tr> <tr><th align="left">Answer:</th></tr> <tr><td bgcolor="#ffffff"><font color="ffffff"> In the single-node case, - <tt>rcu_for_each_nonleaf_node_breadth_first()</tt> is a no-op - and <tt>rcu_for_each_leaf_node()</tt> traverses the single node. + <tt>rcu_for_each_leaf_node()</tt> traverses the single node. </font></td></tr> <tr><td> </td></tr> </table> |