Re: [PATCH 2/2] s390: replace use of system_wq with system_percpu_wq

[Marco Crivellari]

On Mon, Sep 8, 2025 at 10:33 AM Mete Durlu <meted@xxxxxxxxxxxxx> wrote:
>
> If I get this correctly system_wq will be obsolete and users will get
> system_percpu_wq instead, which means local cpu gets to deal with the
> delayed work and its timer and it has an affinity to that cpu via per
> cpu workqueue. In that case;
>
> > diff --git a/arch/s390/kernel/hiperdispatch.c b/arch/s390/kernel/hiperdispatch.c
> > index e7b66d046e8d..85b5508ab62c 100644
> > --- a/arch/s390/kernel/hiperdispatch.c
> > +++ b/arch/s390/kernel/hiperdispatch.c
> > @@ -191,7 +191,7 @@ int hd_enable_hiperdispatch(void)
> >               return 0;
> >       if (hd_online_cores <= hd_entitled_cores)
> >               return 0;
> > -     mod_delayed_work(system_wq, &hd_capacity_work, HD_DELAY_INTERVAL * hd_delay_factor);
> > +     mod_delayed_work(system_percpu_wq, &hd_capacity_work, HD_DELAY_INTERVAL * hd_delay_factor);
> >       hd_update_capacities();
>
> Hiperdispatch's delayed work wouldn't get a noticeable benefit from
> utilizing a per-cpu workqueue. We probably settled on system_wq to
> utilize the global work queue at the time. Would system_unbound_wq
> make more sense here?
>
> Thanks.

Hello,

I will check the code and if it is possible, I will send the v2 with
system_dfl_wq (eg. the current/old system_unbound_wq).

Thanks!
-- 

Marco Crivellari

L3 Support Engineer, Technology & Product

marco.crivellari@xxxxxxxx