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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-08-20 08:35:53 +0400 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-11-16 22:05:56 +0400 |
| commit | 3fbfbf7a3b66ec424042d909f14ba2ddf4372ea8 (patch) | |
| tree | cc364c320a6e23927ecc154a8ef8021dc7d1a9e8 /include/trace/events/rcu.h | |
| parent | aac1cda34b84a9411d6b8d18c3658f094c834911 (diff) | |
| download | linux-3fbfbf7a3b66ec424042d909f14ba2ddf4372ea8.tar.xz | |
rcu: Add callback-free CPUs
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 <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/trace/events/rcu.h')
| -rw-r--r-- | include/trace/events/rcu.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 5bde94d8585b..d4f559b1ec34 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -549,6 +549,7 @@ TRACE_EVENT(rcu_torture_read, * "EarlyExit": rcu_barrier_callback() piggybacked, thus early exit. * "Inc1": rcu_barrier_callback() piggyback check counter incremented. * "Offline": rcu_barrier_callback() found offline CPU + * "OnlineNoCB": rcu_barrier_callback() found online no-CBs CPU. * "OnlineQ": rcu_barrier_callback() found online CPU with callbacks. * "OnlineNQ": rcu_barrier_callback() found online CPU, no callbacks. * "IRQ": An rcu_barrier_callback() callback posted on remote CPU. |