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    SubjectRe: [PATCH -v2 13/18] sched/fair: Propagate an effective runnable_load_avg
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    On 01/09/17 14:21, Peter Zijlstra wrote:
    > The load balancer uses runnable_load_avg as load indicator. For
    > !cgroup this is:
    >
    > runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq
    >
    > That is, a direct sum of all runnable tasks on that runqueue. As
    > opposed to load_avg, which is a sum of all tasks on the runqueue,
    > which includes a blocked component.
    >
    > However, in the cgroup case, this comes apart since the group entities
    > are always runnable, even if most of their constituent entities are
    > blocked.
    >
    > Therefore introduce a runnable_weight which for task entities is the
    > same as the regular weight, but for group entities is a fraction of
    > the entity weight and represents the runnable part of the group
    > runqueue.
    >
    > Then propagate this load through the PELT hierarchy to arrive at an
    > effective runnable load avgerage -- which we should not confuse with
    > the canonical runnable load average.
    >
    > Suggested-by: Tejun Heo <tj@kernel.org>
    > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    > ---
    > include/linux/sched.h | 3
    > kernel/sched/debug.c | 8 ++
    > kernel/sched/fair.c | 173 ++++++++++++++++++++++++++++++++------------------
    > kernel/sched/sched.h | 3
    > 4 files changed, 125 insertions(+), 62 deletions(-)

    [...]

    > @@ -2931,31 +2949,45 @@ static long calc_cfs_shares(struct cfs_r
    >
    > static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
    >
    > -static void update_cfs_shares(struct sched_entity *se)
    > +/*
    > + * Recomputes the group entity based on the current state of its group
    > + * runqueue.
    > + */
    > +static void update_cfs_group(struct sched_entity *se)

    update_cfs_share(s)() is still mentioned in the function header of
    update_tg_load_avg() and update_cfs_rq_load_avg().

    Should we rename those comments with this patch?

    IMHO, the comment for update_tg_load_avg() is still true whereas the one
    for update_cfs_rq_load_avg() mentions cfs_rq->avg as
    cfs_rq->avg.load_avg (or cfs_rq_load_avg()) and update_cfs_group()
    doesn't use it anymore. It's now used in calc_group_runnable() and
    calc_group_shares() instead.

    [...]

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