Use napi_affinity_no_change instead of gve's internal implementation,
simplifying and centralizing the logic.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 drivers/net/ethernet/google/gve/gve_main.c | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 661566db68c8..ad5e85b8c6a5 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -298,18 +298,6 @@ static irqreturn_t gve_intr_dqo(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
-static int gve_is_napi_on_home_cpu(struct gve_priv *priv, u32 irq)
-{
-	int cpu_curr = smp_processor_id();
-	const struct cpumask *aff_mask;
-
-	aff_mask = irq_get_effective_affinity_mask(irq);
-	if (unlikely(!aff_mask))
-		return 1;
-
-	return cpumask_test_cpu(cpu_curr, aff_mask);
-}
-
 int gve_napi_poll(struct napi_struct *napi, int budget)
 {
 	struct gve_notify_block *block;
@@ -383,7 +371,7 @@ int gve_napi_poll_dqo(struct napi_struct *napi, int budget)
 		/* Reschedule by returning budget only if already on the correct
 		 * cpu.
 		 */
-		if (likely(gve_is_napi_on_home_cpu(priv, block->irq)))
+		if (likely(napi_affinity_no_change(block->irq)))
 			return budget;
 
 		/* If not on the cpu with which this queue's irq has affinity
-- 
2.25.1

On Mon, Aug 12, 2024 at 7:57 AM Joe Damato <jdamato@fastly.com> wrote:
>
> Use napi_affinity_no_change instead of gve's internal implementation,
> simplifying and centralizing the logic.
>
> Signed-off-by: Joe Damato <jdamato@fastly.com>
> ---
>  drivers/net/ethernet/google/gve/gve_main.c | 14 +-------------
>  1 file changed, 1 insertion(+), 13 deletions(-)
>
> diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
> index 661566db68c8..ad5e85b8c6a5 100644
> --- a/drivers/net/ethernet/google/gve/gve_main.c
> +++ b/drivers/net/ethernet/google/gve/gve_main.c
> @@ -298,18 +298,6 @@ static irqreturn_t gve_intr_dqo(int irq, void *arg)
>         return IRQ_HANDLED;
>  }
>
> -static int gve_is_napi_on_home_cpu(struct gve_priv *priv, u32 irq)
> -{
> -       int cpu_curr = smp_processor_id();
> -       const struct cpumask *aff_mask;
> -
> -       aff_mask = irq_get_effective_affinity_mask(irq);
> -       if (unlikely(!aff_mask))
> -               return 1;
> -
> -       return cpumask_test_cpu(cpu_curr, aff_mask);
> -}
> -
>  int gve_napi_poll(struct napi_struct *napi, int budget)
>  {
>         struct gve_notify_block *block;
> @@ -383,7 +371,7 @@ int gve_napi_poll_dqo(struct napi_struct *napi, int budget)
>                 /* Reschedule by returning budget only if already on the correct
>                  * cpu.
>                  */
> -               if (likely(gve_is_napi_on_home_cpu(priv, block->irq)))
> +               if (likely(napi_affinity_no_change(block->irq)))

Nice to centralize this code! Evolving this to cache the affinity mask
like the other drivers would probably also require a means to update
the cache when the affinity changes.

>                         return budget;
>
>                 /* If not on the cpu with which this queue's irq has affinity
> --
> 2.25.1
>

On Tue, Aug 13, 2024 at 11:55:31AM -0700, Shailend Chand wrote:
> On Mon, Aug 12, 2024 at 7:57 AM Joe Damato <jdamato@fastly.com> wrote:
> >
> > Use napi_affinity_no_change instead of gve's internal implementation,
> > simplifying and centralizing the logic.
> >
> > Signed-off-by: Joe Damato <jdamato@fastly.com>
> > ---
> >  drivers/net/ethernet/google/gve/gve_main.c | 14 +-------------
> >  1 file changed, 1 insertion(+), 13 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
> > index 661566db68c8..ad5e85b8c6a5 100644
> > --- a/drivers/net/ethernet/google/gve/gve_main.c
> > +++ b/drivers/net/ethernet/google/gve/gve_main.c
> > @@ -298,18 +298,6 @@ static irqreturn_t gve_intr_dqo(int irq, void *arg)
> >         return IRQ_HANDLED;
> >  }
> >
> > -static int gve_is_napi_on_home_cpu(struct gve_priv *priv, u32 irq)
> > -{
> > -       int cpu_curr = smp_processor_id();
> > -       const struct cpumask *aff_mask;
> > -
> > -       aff_mask = irq_get_effective_affinity_mask(irq);
> > -       if (unlikely(!aff_mask))
> > -               return 1;
> > -
> > -       return cpumask_test_cpu(cpu_curr, aff_mask);
> > -}
> > -
> >  int gve_napi_poll(struct napi_struct *napi, int budget)
> >  {
> >         struct gve_notify_block *block;
> > @@ -383,7 +371,7 @@ int gve_napi_poll_dqo(struct napi_struct *napi, int budget)
> >                 /* Reschedule by returning budget only if already on the correct
> >                  * cpu.
> >                  */
> > -               if (likely(gve_is_napi_on_home_cpu(priv, block->irq)))
> > +               if (likely(napi_affinity_no_change(block->irq)))
> 
> Nice to centralize this code! Evolving this to cache the affinity mask
> like the other drivers would probably also require a means to update
> the cache when the affinity changes.

Thanks for taking a look.

The gve driver already calls irq_get_effective_affinity_mask in the
hot path, so I'm planning on submitting a rfcv2 which will do this:

-               if (likely(gve_is_napi_on_home_cpu(priv, block->irq)))
+               const struct cpumask *aff_mask =
+                       irq_get_effective_affinity_mask(block->irq);
+
+               if (likely(napi_affinity_no_change(aff_mask)))
                        return budget;

with a change like that there'd be no behavioral change to gve since
it didn't cache before and still won't be caching after this change.

I think a change can be made to gve in a separate patch set to
support caching the affinity mask and does not need to be included
with this change.

What do you think?

On Tue, Aug 13, 2024 at 2:44 PM Joe Damato <jdamato@fastly.com> wrote:
>
> On Tue, Aug 13, 2024 at 11:55:31AM -0700, Shailend Chand wrote:
> > On Mon, Aug 12, 2024 at 7:57 AM Joe Damato <jdamato@fastly.com> wrote:
> > >
> > > Use napi_affinity_no_change instead of gve's internal implementation,
> > > simplifying and centralizing the logic.
> > >
> > > Signed-off-by: Joe Damato <jdamato@fastly.com>
> > > ---
> > >  drivers/net/ethernet/google/gve/gve_main.c | 14 +-------------
> > >  1 file changed, 1 insertion(+), 13 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
> > > index 661566db68c8..ad5e85b8c6a5 100644
> > > --- a/drivers/net/ethernet/google/gve/gve_main.c
> > > +++ b/drivers/net/ethernet/google/gve/gve_main.c
> > > @@ -298,18 +298,6 @@ static irqreturn_t gve_intr_dqo(int irq, void *arg)
> > >         return IRQ_HANDLED;
> > >  }
> > >
> > > -static int gve_is_napi_on_home_cpu(struct gve_priv *priv, u32 irq)
> > > -{
> > > -       int cpu_curr = smp_processor_id();
> > > -       const struct cpumask *aff_mask;
> > > -
> > > -       aff_mask = irq_get_effective_affinity_mask(irq);
> > > -       if (unlikely(!aff_mask))
> > > -               return 1;
> > > -
> > > -       return cpumask_test_cpu(cpu_curr, aff_mask);
> > > -}
> > > -
> > >  int gve_napi_poll(struct napi_struct *napi, int budget)
> > >  {
> > >         struct gve_notify_block *block;
> > > @@ -383,7 +371,7 @@ int gve_napi_poll_dqo(struct napi_struct *napi, int budget)
> > >                 /* Reschedule by returning budget only if already on the correct
> > >                  * cpu.
> > >                  */
> > > -               if (likely(gve_is_napi_on_home_cpu(priv, block->irq)))
> > > +               if (likely(napi_affinity_no_change(block->irq)))
> >
> > Nice to centralize this code! Evolving this to cache the affinity mask
> > like the other drivers would probably also require a means to update
> > the cache when the affinity changes.
>
> Thanks for taking a look.
>
> The gve driver already calls irq_get_effective_affinity_mask in the
> hot path, so I'm planning on submitting a rfcv2 which will do this:
>
> -               if (likely(gve_is_napi_on_home_cpu(priv, block->irq)))
> +               const struct cpumask *aff_mask =
> +                       irq_get_effective_affinity_mask(block->irq);
> +
> +               if (likely(napi_affinity_no_change(aff_mask)))
>                         return budget;
>
> with a change like that there'd be no behavioral change to gve since
> it didn't cache before and still won't be caching after this change.
>
> I think a change can be made to gve in a separate patch set to
> support caching the affinity mask and does not need to be included
> with this change.
>
> What do you think?

Sounds good!