rcu: Add documentation for the new rcuexp debugfs trace file This commit adds the documentation of the rcuexp debugfs trace file that records statistics for expedited grace periods.
Signed-off-by: Paul E. McKenney <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> b/Documentation/RCU/trace.txt | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index 79ce989..c776968 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -41,6 +41,8 @@ also rcu/rcu_preempt) the following files will be present: rcudata: Displays fields in struct rcu_data. +rcuexp: + Displays statistics for expedited grace periods. rcugp: Displays grace-period counters. rcuhier: @@ -233,6 +235,45 @@ o "ktl" is the low-order 16 bits (in hexadecimal) of the count of This field is displayed only for CONFIG_RCU_BOOST kernels. +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 + +These fields are as follows: + +o "s" is the starting sequence number. + +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 + 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 "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: completed=31249 gpnum=31250 age=1 max=18 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
