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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-02-28 11:02:21 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-04-24 20:55:20 -0700 |
| commit | c57afe80db4e169135eb675acc2d241e26cc064e (patch) | |
| tree | ec011600725a2884efdca6f4c187ea7e3fa4d277 /kernel/rcutree.c | |
| parent | 2ee3dc80660ac8285a37e662fd91b2e45c46f06a (diff) | |
| download | linux-c57afe80db4e169135eb675acc2d241e26cc064e.tar.gz linux-c57afe80db4e169135eb675acc2d241e26cc064e.tar.bz2 linux-c57afe80db4e169135eb675acc2d241e26cc064e.zip | |
rcu: Make RCU_FAST_NO_HZ account for pauses out of idle
Both Steven Rostedt's new idle-capable trace macros and the RCU_NONIDLE()
macro can cause RCU to momentarily pause out of idle without the rest
of the system being involved. This can cause rcu_prepare_for_idle()
to run through its state machine too quickly, which can in turn result
in needless scheduling-clock interrupts.
This commit therefore adds code to enable rcu_prepare_for_idle() to
distinguish between an initial entry to idle on the one hand (which needs
to advance the rcu_prepare_for_idle() state machine) and an idle reentry
due to idle-capable trace macros and RCU_NONIDLE() on the other hand
(which should avoid advancing the rcu_prepare_for_idle() state machine).
Additional state is maintained to allow the timer to be correctly reposted
when returning after a momentary pause out of idle, and even more state
is maintained to detect when new non-lazy callbacks have been enqueued
(which may require re-evaluation of the approach to idleness).
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 1050d6d3922c..403306b86e78 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1829,6 +1829,8 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), rdp->qlen++; if (lazy) rdp->qlen_lazy++; + else + rcu_idle_count_callbacks_posted(); if (__is_kfree_rcu_offset((unsigned long)func)) trace_rcu_kfree_callback(rsp->name, head, (unsigned long)func, |