From: Paul E. McKenney Date: Tue, 7 Sep 2010 21:23:09 +0000 (-0700) Subject: rcu: Add tracing data to support queueing models X-Git-Tag: v2.6.37-rc1~215^2~7 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=269dcc1c2ec25864308ee03a3fa26ea819d9f5d0;p=pandora-kernel.git 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 . Signed-off-by: Paul E. McKenney --- Reading git-diff-tree failed