Messages in this thread | | | Date | Thu, 20 Jun 2013 14:01:07 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [RFC PATCH 2/4] sched: Consolidate nohz cpu load prelude code |
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On Thu, Jun 20, 2013 at 10:45:39PM +0200, Frederic Weisbecker wrote: > Gather the common code that computes the pending idle cpu load > to decay. > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Li Zhong <zhong@linux.vnet.ibm.com> > Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Alex Shi <alex.shi@intel.com> > Cc: Paul Turner <pjt@google.com> > Cc: Mike Galbraith <efault@gmx.de> > Cc: Vincent Guittot <vincent.guittot@linaro.org> > --- > kernel/sched/proc.c | 40 ++++++++++++++-------------------------- > 1 files changed, 14 insertions(+), 26 deletions(-) > > diff --git a/kernel/sched/proc.c b/kernel/sched/proc.c > index bb3a6a0..030528a 100644 > --- a/kernel/sched/proc.c > +++ b/kernel/sched/proc.c > @@ -470,11 +470,14 @@ decay_load_missed(unsigned long load, unsigned long missed_updates, int idx) > * scheduler tick (TICK_NSEC). With tickless idle this will not be called > * every tick. We fix it up based on jiffies. > */ > -static void __update_cpu_load(struct rq *this_rq, unsigned long this_load, > - unsigned long pending_updates) > +static void __update_cpu_load(struct rq *this_rq, unsigned long this_load) > { > + unsigned long curr_jiffies = ACCESS_ONCE(jiffies);
Isn't jiffies declared volatile? (Looks that way to me.) If so, there is no need for ACCESS_ONCE().
> + unsigned long pending_updates; > int i, scale; > > + pending_updates = curr_jiffies - this_rq->last_load_update_tick; > + this_rq->last_load_update_tick = curr_jiffies; > this_rq->nr_load_updates++; > > /* Update our load: */ > @@ -521,20 +524,15 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load, > */ > void update_idle_cpu_load(struct rq *this_rq) > { > - unsigned long curr_jiffies = ACCESS_ONCE(jiffies); > unsigned long load = this_rq->load.weight; > - unsigned long pending_updates; > > /* > * bail if there's load or we're actually up-to-date. > */ > - if (load || curr_jiffies == this_rq->last_load_update_tick) > + if (load || jiffies == this_rq->last_load_update_tick) > return; > > - pending_updates = curr_jiffies - this_rq->last_load_update_tick; > - this_rq->last_load_update_tick = curr_jiffies; > - > - __update_cpu_load(this_rq, load, pending_updates); > + __update_cpu_load(this_rq, load); > } > > /* > @@ -543,22 +541,16 @@ void update_idle_cpu_load(struct rq *this_rq) > void update_cpu_load_nohz(void) > { > struct rq *this_rq = this_rq(); > - unsigned long curr_jiffies = ACCESS_ONCE(jiffies); > - unsigned long pending_updates; > > - if (curr_jiffies == this_rq->last_load_update_tick) > + if (jiffies == this_rq->last_load_update_tick) > return; > > raw_spin_lock(&this_rq->lock); > - pending_updates = curr_jiffies - this_rq->last_load_update_tick; > - if (pending_updates) { > - this_rq->last_load_update_tick = curr_jiffies; > - /* > - * We were idle, this means load 0, the current load might be > - * !0 due to remote wakeups and the sort. > - */ > - __update_cpu_load(this_rq, 0, pending_updates); > - } > + /* > + * We were idle, this means load 0, the current load might be > + * !0 due to remote wakeups and the sort. > + */ > + __update_cpu_load(this_rq, 0); > raw_spin_unlock(&this_rq->lock); > } > #endif /* CONFIG_NO_HZ */ > @@ -568,11 +560,7 @@ void update_cpu_load_nohz(void) > */ > void update_cpu_load_active(struct rq *this_rq) > { > - /* > - * See the mess around update_idle_cpu_load() / update_cpu_load_nohz(). > - */ > - this_rq->last_load_update_tick = jiffies; > - __update_cpu_load(this_rq, this_rq->load.weight, 1); > + __update_cpu_load(this_rq, this_rq->load.weight); > > calc_load_account_active(this_rq); > } > -- > 1.7.5.4 >
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