Hi Vincent,
On 08/26/2014 04:36 PM, Vincent Guittot wrote:
> capacity_orig is only changed for system with a SMT sched_domain level in
> order
I think I had asked this before, but why only capacity_orig? The
capacity of a group is also being updated the same way. This patch fixes
the capacity of a group to reflect the capacity of the heterogeneous
CPUs in it, this capacity being both the full capacity of the group:
capacity_orig and the capacity available for the fair tasks. So I feel
in the subject as well as the changelog it would suffice to say 'capacity'.
> to reflect the lower capacity of CPUs. Heterogenous system also have to
> reflect an
> original capacity that is different from the default value.
>
> Create a more generic function arch_scale_cpu_capacity that can be also used
> by
> non SMT platform to set capacity_orig.
>
> The weak behavior of arch_scale_cpu_capacity is the previous SMT one in order
> to
> keep backward compatibility in the use of capacity_orig.
>
> arch_scale_smt_capacity and default_scale_smt_capacity have been removed as
> they were not use elsewhere than in arch_scale_cpu_capacity.
>
> Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org>
> ---
> kernel/sched/fair.c | 25 ++++++-------------------
> 1 file changed, 6 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index b85e9f7..8176bda 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5705,19 +5705,12 @@ unsigned long __weak arch_scale_freq_capacity(struct
> sched_domain *sd, int cpu)
> return default_scale_capacity(sd, cpu);
> }
>
> -static unsigned long default_scale_smt_capacity(struct sched_domain *sd, int
> cpu)
> +unsigned long __weak arch_scale_cpu_capacity(struct sched_domain *sd, int
> cpu)
> {
> - unsigned long weight = sd->span_weight;
> - unsigned long smt_gain = sd->smt_gain;
> + if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1))
> + return sd->smt_gain / sd->span_weight;
>
> - smt_gain /= weight;
> -
> - return smt_gain;
> -}
> -
> -unsigned long __weak arch_scale_smt_capacity(struct sched_domain *sd, int
> cpu)
> -{
> - return default_scale_smt_capacity(sd, cpu);
> + return SCHED_CAPACITY_SCALE;
> }
>
> static unsigned long scale_rt_capacity(int cpu)
> @@ -5756,18 +5749,12 @@ static unsigned long scale_rt_capacity(int cpu)
>
> static void update_cpu_capacity(struct sched_domain *sd, int cpu)
> {
> - unsigned long weight = sd->span_weight;
> unsigned long capacity = SCHED_CAPACITY_SCALE;
> struct sched_group *sdg = sd->groups;
>
> - if ((sd->flags & SD_SHARE_CPUCAPACITY) && weight > 1) {
> - if (sched_feat(ARCH_CAPACITY))
Aren't you missing this check above? I understand that it is not
crucial, but that would also mean removing ARCH_CAPACITY sched_feat
altogether, wouldn't it?
Regards
Preeti U Murthy
> - capacity *= arch_scale_smt_capacity(sd, cpu);
> - else
> - capacity *= default_scale_smt_capacity(sd, cpu);
> + capacity *= arch_scale_cpu_capacity(sd, cpu);
>
> - capacity >>= SCHED_CAPACITY_SHIFT;
> - }
> + capacity >>= SCHED_CAPACITY_SHIFT;
>
> sdg->sgc->capacity_orig = capacity;
>
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