lkml.org 
[lkml]   [2020]   [Apr]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 2/4] sched/deadline: Improve admission control for asymmetric CPU capacities
    On 04/09/20 19:29, Dietmar Eggemann wrote:

    [...]

    > Maybe we can do a hybrid. We have rd->span and rd->sum_cpu_capacity and
    > with the help of an extra per-cpu cpumask we could just
    >
    > DEFINE_PER_CPU(cpumask_var_t, dl_bw_mask);
    >
    > dl_bw_cpus(int i) {
    >
    > struct cpumask *cpus = this_cpu_cpumask_var_ptr(dl_bw_mask);
    > ...
    > cpumask_and(cpus, rd->span, cpu_active_mask);
    >
    > return cpumask_weight(cpus);
    > }
    >
    > and
    >
    > dl_bw_capacity(int i) {
    >
    > struct cpumask *cpus = this_cpu_cpumask_var_ptr(dl_bw_mask);
    > ...
    > cpumask_and(cpus, rd->span, cpu_active_mask);
    > if (cpumask_equal(cpus, rd->span))
    > return rd->sum_cpu_capacity;
    >
    > for_each_cpu(i, cpus)
    > cap += capacity_orig_of(i);
    >
    > return cap;
    > }
    >
    > So only in cases in which rd->span and cpu_active_mask differ we would
    > have to sum up again.

    I haven't followed this discussion closely, so I could be missing something
    here.

    In sched_cpu_dying() we call set_rq_offline() which clears the cpu in
    rq->rd->online.

    So the way I read the code

    rd->online = cpumask_and(rd->span, cpu_active_mask)

    But I could have easily missed some detail.

    Regardless, it seems to me that DL is working around something not right in the
    definition of rd->span or using the wrong variable.

    My 2p :-). I have to go back and read the discussion in more detail.

    Thanks

    --
    Qais Yousef

    \
     
     \ /
      Last update: 2020-04-14 13:41    [W:2.663 / U:0.128 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site