On Fri, Oct 23, 2020 at 3:48 PM <[email protected]> wrote:
>
> From: Guo Ren <[email protected]>
>
> If "echo 3 > /proc/irq/1/smp_affinity", we want irq 1 could be
> broadcast to CPU0 & CPU1 and one of them would pick up the irq
> handler.
>
> But current implementation couldn't let multi CPUs process the
> same IRQ concurrent.
>
> Signed-off-by: Guo Ren <[email protected]>
> ---
> drivers/irqchip/irq-sifive-plic.c | 23 ++++++-----------------
> 1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index 2e56576..0003322 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -114,15 +114,12 @@ static inline void plic_irq_toggle(const struct cpumask *mask,
> static void plic_irq_unmask(struct irq_data *d)
> {
> struct cpumask amask;
> - unsigned int cpu;
> struct plic_priv *priv = irq_get_chip_data(d->irq);
>
> cpumask_and(&amask, &priv->lmask, cpu_online_mask);
> - cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
> - &amask);
> - if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
> - return;
> - plic_irq_toggle(cpumask_of(cpu), d, 1);
> + cpumask_and(&amask, &amask, irq_data_get_affinity_mask(d));
> +
> + plic_irq_toggle(&amask, d, 1);
> }
>
> static void plic_irq_mask(struct irq_data *d)
> @@ -136,24 +133,16 @@ static void plic_irq_mask(struct irq_data *d)
> static int plic_set_affinity(struct irq_data *d,
> const struct cpumask *mask_val, bool force)
> {
> - unsigned int cpu;
> struct cpumask amask;
> struct plic_priv *priv = irq_get_chip_data(d->irq);
>
> cpumask_and(&amask, &priv->lmask, mask_val);
> + cpumask_and(&amask, &amask, cpu_online_mask);
>
> - if (force)
> - cpu = cpumask_first(&amask);
> - else
> - cpu = cpumask_any_and(&amask, cpu_online_mask);
> -
> - if (cpu >= nr_cpu_ids)
> - return -EINVAL;
> + irq_data_update_effective_affinity(d, &amask);
>
> plic_irq_toggle(&priv->lmask, d, 0);
> - plic_irq_toggle(cpumask_of(cpu), d, 1);
> -
> - irq_data_update_effective_affinity(d, cpumask_of(cpu));
> + plic_irq_toggle(&amask, d, 1);
>
> return IRQ_SET_MASK_OK_DONE;
> }
> --
> 2.7.4
>
In the past, a similar patch was proposed by Zong Li (SiFive). We
have good reasons to not allow multiple CPUs handle the same IRQ.
Refer, https://lkml.org/lkml/2020/4/26/201
NACK from my side.
Regards,
Anup
On Fri, Oct 23, 2020 at 8:17 PM Anup Patel <[email protected]> wrote:
>
> On Fri, Oct 23, 2020 at 3:48 PM <[email protected]> wrote:
> >
> > From: Guo Ren <[email protected]>
> >
> > If "echo 3 > /proc/irq/1/smp_affinity", we want irq 1 could be
> > broadcast to CPU0 & CPU1 and one of them would pick up the irq
> > handler.
> >
> > But current implementation couldn't let multi CPUs process the
> > same IRQ concurrent.
> >
> > Signed-off-by: Guo Ren <[email protected]>
> > ---
> > drivers/irqchip/irq-sifive-plic.c | 23 ++++++-----------------
> > 1 file changed, 6 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> > index 2e56576..0003322 100644
> > --- a/drivers/irqchip/irq-sifive-plic.c
> > +++ b/drivers/irqchip/irq-sifive-plic.c
> > @@ -114,15 +114,12 @@ static inline void plic_irq_toggle(const struct cpumask *mask,
> > static void plic_irq_unmask(struct irq_data *d)
> > {
> > struct cpumask amask;
> > - unsigned int cpu;
> > struct plic_priv *priv = irq_get_chip_data(d->irq);
> >
> > cpumask_and(&amask, &priv->lmask, cpu_online_mask);
> > - cpu = cpumask_any_and(irq_data_get_affinity_mask(d),
> > - &amask);
> > - if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
> > - return;
> > - plic_irq_toggle(cpumask_of(cpu), d, 1);
> > + cpumask_and(&amask, &amask, irq_data_get_affinity_mask(d));
> > +
> > + plic_irq_toggle(&amask, d, 1);
> > }
> >
> > static void plic_irq_mask(struct irq_data *d)
> > @@ -136,24 +133,16 @@ static void plic_irq_mask(struct irq_data *d)
> > static int plic_set_affinity(struct irq_data *d,
> > const struct cpumask *mask_val, bool force)
> > {
> > - unsigned int cpu;
> > struct cpumask amask;
> > struct plic_priv *priv = irq_get_chip_data(d->irq);
> >
> > cpumask_and(&amask, &priv->lmask, mask_val);
> > + cpumask_and(&amask, &amask, cpu_online_mask);
> >
> > - if (force)
> > - cpu = cpumask_first(&amask);
> > - else
> > - cpu = cpumask_any_and(&amask, cpu_online_mask);
> > -
> > - if (cpu >= nr_cpu_ids)
> > - return -EINVAL;
> > + irq_data_update_effective_affinity(d, &amask);
> >
> > plic_irq_toggle(&priv->lmask, d, 0);
> > - plic_irq_toggle(cpumask_of(cpu), d, 1);
> > -
> > - irq_data_update_effective_affinity(d, cpumask_of(cpu));
> > + plic_irq_toggle(&amask, d, 1);
> >
> > return IRQ_SET_MASK_OK_DONE;
> > }
> > --
> > 2.7.4
> >
>
> In the past, a similar patch was proposed by Zong Li (SiFive). We
> have good reasons to not allow multiple CPUs handle the same IRQ.
>
> Refer, https://lkml.org/lkml/2020/4/26/201
>
> NACK from my side.
Thx for sharing the information, I agree with Zong Li & Greentime's
aspect: Don't limit the usage of PLIC! We could let (one hart -> one
irq) as default.
I also agree that using irq broadcast indiscriminately can cause
performance problems. (Anup and Mark Z's view)
I think you've discussed enough at that time and l won't persist the patch.
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/