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| author | Joel Fernandes (Google) <joel@joelfernandes.org> | 2018-06-24 21:34:51 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-08-29 17:54:30 +0200 |
| commit | ea24c125fe79fd966a4f59768d3d70142a9eb18d (patch) | |
| tree | 4f0b51423d81013796d0ef18a5afdedce5e09d3e /Documentation/RCU/Design | |
| parent | doc: Fix broken RCU-requirements link to LKML archive (diff) | |
| download | linux-ea24c125fe79fd966a4f59768d3d70142a9eb18d.tar.xz linux-ea24c125fe79fd966a4f59768d3d70142a9eb18d.zip | |
doc: Improve rcu_dynticks::dynticks documentation
The very useful RCU Data-Structures describes that the dynticks counter
of the rcu_dynticks data structure is incremented when we transitions to
or from dynticks-idle mode. However it doesn't mention that it is also
incremented due to transitions to and from user mode which for dynticks
purposes is an extended quiescent state.
I found this with tracing calls to rcu_dynticks_eqs_enter which can also
happen from rcu_user_enter. Lets add this information to the
Data-Structures document.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/RCU/Design')
| -rw-r--r-- | Documentation/RCU/Design/Data-Structures/Data-Structures.html | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/Documentation/RCU/Design/Data-Structures/Data-Structures.html b/Documentation/RCU/Design/Data-Structures/Data-Structures.html index f5120a00f511..50be87e59937 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 |