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Diffstat (limited to 'Documentation/RCU/Design')
| -rw-r--r-- | Documentation/RCU/Design/Data-Structures/Data-Structures.html | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html index 2ab38ee420c5..38d6d800761f 100644 --- a/Documentation/RCU/Design/Data-Structures/Data-Structures.html +++ b/Documentation/RCU/Design/Data-Structures/Data-Structures.html @@ -1185,6 +1185,9 @@ Its fields are as follows: 1 int dynticks_nesting; 2 int dynticks_nmi_nesting; 3 atomic_t dynticks; + 4 bool rcu_need_heavy_qs; + 5 unsigned long rcu_qs_ctr; + 6 bool rcu_urgent_qs; </pre> <p>The <tt>->dynticks_nesting</tt> field counts the @@ -1198,11 +1201,32 @@ NMIs are counted by the <tt>->dynticks_nmi_nesting</tt> field, except that NMIs that interrupt non-dyntick-idle execution are not counted. -</p><p>Finally, the <tt>->dynticks</tt> field counts the corresponding +</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. +</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 +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>The <tt>->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. + +</p><p>Finally, the <tt>->rcu_urgent_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, with the various other fields indicating +just how badly RCU wants this quiescent state. +This flag is checked by RCU's context-switch and <tt>cond_resched()</tt> +code, which, if nothing else, non-atomically increment <tt>->rcu_qs_ctr</tt> +in response. + <table> <tr><th> </th></tr> <tr><th align="left">Quick Quiz:</th></tr> |