[Apologies if threading mangled, all headers written by hand] On 04/04/2013 07:30 AM, Alex Shi wrote: > The cpu's utilization is to measure how busy is the cpu. > util = cpu_rq(cpu)->avg.runnable_avg_sum * SCHED_POEWR_SCALE > / cpu_rq(cpu)->avg.runnable_avg_period; > > Since the util is no more than 1, we scale its value with 1024, same as > SCHED_POWER_SCALE and set the FULL_UTIL as 1024. > > In later power aware scheduling, we are sensitive for how busy of the > cpu. Since as to power consuming, it is tight related with cpu busy > time. > > BTW, rq->util can be used for any purposes if needed, not only power > scheduling. > > Signed-off-by: Alex Shi <alex....@intel.com> > --- > include/linux/sched.h | 2 +- > kernel/sched/debug.c | 1 + > kernel/sched/fair.c | 5 +++++ > kernel/sched/sched.h | 4 ++++ > 4 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 5a4cf37..226a515 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -793,7 +793,7 @@ enum cpu_idle_type { > #define SCHED_LOAD_SCALE (1L << SCHED_LOAD_SHIFT) > > /* > - * Increase resolution of cpu_power calculations > + * Increase resolution of cpu_power and rq->util calculations > */ > #define SCHED_POWER_SHIFT 10 > #define SCHED_POWER_SCALE (1L << SCHED_POWER_SHIFT) > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c > index 75024a6..f5db759 100644 > --- a/kernel/sched/debug.c > +++ b/kernel/sched/debug.c > @@ -311,6 +311,7 @@ do { > \ > > P(ttwu_count); > P(ttwu_local); > + P(util); > > #undef P > #undef P64 > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 2e49c3f..7124244 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -1495,8 +1495,13 @@ static void update_cfs_rq_blocked_load(struct cfs_rq > *cfs_rq, int force_update) > > static inline void update_rq_runnable_avg(struct rq *rq, int runnable) > { > + u32 period; > __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable); > __update_tg_runnable_avg(&rq->avg, &rq->cfs); > + > + period = rq->avg.runnable_avg_period ? rq->avg.runnable_avg_period : 1; > + rq->util = (u64)(rq->avg.runnable_avg_sum << SCHED_POWER_SHIFT) > + / period;
Greetings, Alex. That cast achieves nothing where it is. If the shift has overflowed, then you've already lost information; and if it can't overflow, then it's not needed at all. It's itsy-bitsy, but note that there exists a div_u64(u64 dividend, u32 divisor) helper which may be implemented to be superior to just '/'. (And also note that the assignment to ``period'' is a good candidate for gcc's ``?:'' operator.) If you pull the cast inside the brackets, then you may add my Reviewed-by: Phil Carmody <pc+l...@asdf.org> Cheers, Phil > } > > /* Add the load generated by se into cfs_rq's child load-average */ > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 804ee41..8682110 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -351,6 +351,9 @@ extern struct root_domain def_root_domain; > > #endif /* CONFIG_SMP */ > > +/* full cpu utilization */ > +#define FULL_UTIL SCHED_POWER_SCALE > + > /* > * This is the main, per-CPU runqueue data structure. > * > @@ -482,6 +485,7 @@ struct rq { > #endif > > struct sched_avg avg; > + unsigned int util; > }; > > static inline int cpu_of(struct rq *rq) > -- "In a world of magnets and miracles" -- Insane Clown Posse, Miracles, 2009. Much derided. "Magnets, how do they work" -- Pink Floyd, High Hopes, 1994. Lauded as lyrical geniuses. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/