lkml.org 
[lkml]   [2015]   [Sep]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH 1/2] nohz: Affine unpinned timers to housekeepers
    From
    Date
    On Tue, 2015-09-01 at 22:47 +0200, Frederic Weisbecker wrote:
    > On Tue, Sep 01, 2015 at 07:14:13PM +0000, Jiang, Yunhong wrote:
    > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    > > > index 8b864ec..0902e4d 100644
    > > > --- a/kernel/sched/core.c
    > > > +++ b/kernel/sched/core.c
    > > > @@ -623,18 +623,21 @@ int get_nohz_timer_target(void)
    > > > int i, cpu = smp_processor_id();
    > > > struct sched_domain *sd;
    > > >
    > > > - if (!idle_cpu(cpu))
    > > > + if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
    > > > return cpu;
    > > >
    > > > rcu_read_lock();
    > > > for_each_domain(cpu, sd) {
    > > > for_each_cpu(i, sched_domain_span(sd)) {
    > > > - if (!idle_cpu(i)) {
    > > > + if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
    > >
    > > Hi, Frederic, sorry for a naive question. Per my understanding, the tick_nohz_full_mask is added to cpu_isolated_map in
    > > sched_init_smp(), and the cpu_isolated_map is excluded from sched_domain in init_sched_domains(), so why check here?
    >
    > Very good observation! But it's better to keep this check in the domain loop in
    > case things change in the future such as removing that cpu_isolated_map inclusion
    > or other suprises.

    IMHO, nohz_full -> cpu_isolated_map removal really wants to happen.
    NO_HZ_FULL_ALL currently means "Woohoo, next stop NR_CPUS=0".

    -Mike



    \
     
     \ /
      Last update: 2015-09-02 12:01    [W:4.954 / U:0.032 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site