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    SubjectRe: [PATCH 0/2] sched: add trace event for per-entity tracking
    From
    Alex,

    On Mon, Jul 1, 2013 at 4:06 PM, Alex Shi <alex.shi@intel.com> wrote:
    > On 07/01/2013 03:10 PM, Lei Wen wrote:
    >> Thanks for the per-entity tracking feature, we could know the details of
    >> each task by its help.
    >> This patch add its trace support, so that we could quickly know the system
    >> status in a large time scale, like now we may get each runqueue's usage ratio by:
    >>
    >> cfs_rq's usage ratio = cfs_rq->runnable_load_avg/cfs_rq->load.weight
    >>
    >
    > the direct usage ratio is rq.avg.runnable_avg_sum / rq.avg.runnable_avg_period.


    From the parsed data diagram, seem more pretty than my previous use
    load as the calculation one. :)
    BTW, do you think there is some meaning for doing below calculation?
    cfs_rq->runnable_load_avg/cfs_rq->load.weight

    I think by this calculation from the
    runnable_avg_load/blocked_avg_load trace result,
    we may catch some abnormal load distribution when debugging.


    >
    > one patch from obsolete power-scheduling could be reference for this:
    > git@github.com:alexshi/power-scheduling.git power-scheduling
    >
    > From 081cd4bcbccfaa1930b031e4dfbf9d23b8c0d5ab Mon Sep 17 00:00:00 2001
    > From: Alex Shi <alex.shi@intel.com>
    > Date: Fri, 7 Dec 2012 21:37:58 +0800
    > Subject: [PATCH 02/23] sched: log the cpu utilization at rq
    >
    > 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.shi@intel.com>


    Nice patch, would it be merged? :)

    Thanks,
    Lei
    > ---
    > 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 9539597..4e4d9ee 100644
    > --- a/include/linux/sched.h
    > +++ b/include/linux/sched.h
    > @@ -794,7 +794,7 @@ 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;
    > }
    >
    > /* 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)
    > --
    > 1.7.12
    >
    > --
    > Thanks
    > Alex
    > --
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