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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-09-07 14:23:09 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-09-23 09:16:53 -0700
commit269dcc1c2ec25864308ee03a3fa26ea819d9f5d0 (patch)
tree1c81ee6a9151ab1580628f6e9f85c469ceccb5c0 /kernel/rcutree.h
parent0ddea0ead2ced99eaaaddff2beb755381e5c89f8 (diff)
rcu: Add tracing data to support queueing models
The current tracing data is not sufficient to deduce the average time that a callback spends waiting for a grace period to end. Add three per-CPU counters recording the number of callbacks invoked (ci), the number of callbacks orphaned (co), and the number of callbacks adopted (ca). Given the existing callback queue length (ql), the average wait time in absence of CPU hotplug operations is ql/ci. The units of wait time will be in terms of the duration over which ci was measured. In the presence of CPU hotplug operations, there is room for argument, but ql/(ci-co+ca) won't steer you too far wrong. Also fixes a typo called out by Lucas De Marchi <lucas.de.marchi@gmail.com>. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.h')
-rw-r--r--kernel/rcutree.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 7918ba61873f..91d4170c5c13 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -202,6 +202,9 @@ struct rcu_data {
long qlen; /* # of queued callbacks */
long qlen_last_fqs_check;
/* qlen at last check for QS forcing */
+ unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */
+ unsigned long n_cbs_orphaned; /* RCU cbs sent to orphanage. */
+ unsigned long n_cbs_adopted; /* RCU cbs adopted from orphanage. */
unsigned long n_force_qs_snap;
/* did other CPU force QS recently? */
long blimit; /* Upper limit on a processed batch */

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