linux/kernel/rcutree_trace.c, branch v3.8

rcu: Separate accounting of callbacks from callback-free CPUs

2012-11-16T18:05:57Z

Currently, callback invocations from callback-free CPUs are accounted to the CPU that registered the callback, but using the same field that is used for normal callbacks. This makes it impossible to determine from debugfs output whether callbacks are in fact being diverted. This commit therefore adds a separate ->n_nocbs_invoked field in the rcu_data structure in which diverted callback invocations are counted. RCU's debugfs tracing still displays normal callback invocations using ci=, but displayed diverted callbacks with nci=. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney

rcu: Add callback-free CPUs

2012-11-16T18:05:56Z

RCU callback execution can add significant OS jitter and also can degrade both scheduling latency and, in asymmetric multiprocessors, energy efficiency. This commit therefore adds the ability for selected CPUs ("rcu_nocbs=" boot parameter) to have their callbacks offloaded to kthreads. If the "rcu_nocb_poll" boot parameter is also specified, these kthreads will do polling, removing the need for the offloaded CPUs to do wakeups. At least one CPU must be doing normal callback processing: currently CPU 0 cannot be selected as a no-CBs CPU. In addition, attempts to offline the last normal-CBs CPU will fail. This feature was inspired by Jim Houston's and Joe Korty's JRCU, and this commit includes fixes to problems located by Fengguang Wu's kbuild test robot. [ paulmck: Added gfp.h include file as suggested by Fengguang Wu. ] Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney

rcu: Add tracing for synchronize_sched_expedited()

2012-11-08T19:57:07Z

This commit adds a per-RCU-flavor "rcuexp" file that dumps out statistics for synchonize_sched_expedited(). Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney

rcu: Remove old debugfs interfaces and also RCU flavor name

2012-11-08T19:56:44Z

This commit removes the old debugfs interfaces, so that the new directory-per-RCU-flavor versions remain. Because the RCU flavor is given by the directory name, there is no need to print it out, so remove the name from the printout. Signed-off-by: Michael Wang Signed-off-by: Paul E. McKenney

rcu: split 'rcuhier' to each flavor

2012-11-08T19:55:45Z

This patch add new 'rcuhier' to each flavor's folder, now we could use: 'cat /debugfs/rcu/rsp/rcuhier' to get the selected rsp info. Signed-off-by: Michael Wang Signed-off-by: Paul E. McKenney

rcu: split 'rcugp' to each flavor

2012-11-08T19:55:44Z

This patch add new 'rcugp' to each flavor's folder, now we could use: 'cat /debugfs/rcu/rsp/rcugp' to get the selected rsp info. Signed-off-by: Michael Wang Signed-off-by: Paul E. McKenney

rcu: split 'rcuboost' to each flavor

2012-11-08T19:55:42Z

This patch add new 'rcuboost' to each flavor's folder, now we could use: 'cat /debugfs/rcu/rsp/rcuboost' to get the selected rsp info. Signed-off-by: Michael Wang Signed-off-by: Paul E. McKenney

rcu: split 'rcubarrier' to each flavor

2012-11-08T19:55:41Z

This patch add new 'rcubarrier' to each flavor's folder, now we could use: 'cat /debugfs/rcu/rsp/rcubarrier' to get the selected rsp info. Signed-off-by: Michael Wang Signed-off-by: Paul E. McKenney

rcu: Fix tracing formatting

2012-11-08T19:55:30Z

The rcu_state structure's ->completed field is unsigned long, so this commit adjusts show_one_rcugp()'s printf() format to suit. Also add the required ACCESS_ONCE() directives while we are in this function. Signed-off-by: Paul E. McKenney

rcu: Remove the interface "rcudata.csv"

2012-11-08T19:50:19Z

This patch removes the interface "rcudata.csv" since it is apparently not used. Signed-off-by: Michael Wang Signed-off-by: Paul E. McKenney