rcu: Add fastpath bypassing funnel locking

[firefly-linux-kernel-4.4.55.git] / Documentation / RCU / trace.txt

diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
index 08651da15448e27f8f2fb574c7cd51cde67815c6..97f17e9decdaeced345689e9eb410a79f642b10d 100644 (file)
--- a/Documentation/RCU/trace.txt
+++ b/Documentation/RCU/trace.txt
@@ -237,42 +237,26 @@ o "ktl" is the low-order 16 bits (in hexadecimal) of the count of
 
 The output of "cat rcu/rcu_preempt/rcuexp" looks as follows:
 
-s=21872 d=21872 w=0 tf=0 wd1=0 wd2=0 n=0 sc=21872 dt=21872 dl=0 dx=21872
+s=21872 wd0=0 wd1=0 wd2=0 wd3=5 n=0 enq=0 sc=21872
 
 These fields are as follows:
 
-o      "s" is the starting sequence number.
+o      "s" is the sequence number, with an odd number indicating that
+       an expedited grace period is in progress.
 
-o      "d" is the ending sequence number.  When the starting and ending
-       numbers differ, there is an expedited grace period in progress.
-
-o      "w" is the number of times that the sequence numbers have been
-       in danger of wrapping.
-
-o      "tf" is the number of times that contention has resulted in a
-       failure to begin an expedited grace period.
-
-o      "wd1" and "wd2" are the number of times that an attempt to
-       start an expedited grace period found that someone else had
-       completed an expedited grace period that satisfies the
+o      "wd0", "wd1", "wd2", and "wd3" are the number of times that an
+       attempt to start an expedited grace period found that someone
+       else had completed an expedited grace period that satisfies the
        attempted request.  "Our work is done."
 
-o      "n" is number of times that contention was so great that
-       the request was demoted from an expedited grace period to
-       a normal grace period.
+o      "n" is number of times that a concurrent CPU-hotplug operation
+       forced a fallback to a normal grace period.
+
+o      "enq" is the number of quiescent states still outstanding.
 
 o      "sc" is the number of times that the attempt to start a
        new expedited grace period succeeded.
 
-o      "dt" is the number of times that we attempted to update
-       the "d" counter.
-
-o      "dl" is the number of times that we failed to update the "d"
-       counter.
-
-o      "dx" is the number of times that we succeeded in updating
-       the "d" counter.
-
 
 The output of "cat rcu/rcu_preempt/rcugp" looks as follows: