linux-kernel - Re: [PATCH net-next] tg3: Link IRQs to NAPI instances

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Message-ID: <ZuMvY6_MolZYMT9m@LQ3V64L9R2.homenet.telecomitalia.it>
Date: Thu, 12 Sep 2024 20:13:55 +0200
From: Joe Damato <jdamato@...tly.com>
To: Michael Chan <michael.chan@...adcom.com>
Cc: netdev@...r.kernel.org, Pavan Chebbi <pavan.chebbi@...adcom.com>,
	Michael Chan <mchan@...adcom.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next] tg3: Link IRQs to NAPI instances

On Thu, Sep 12, 2024 at 11:04:02AM -0700, Michael Chan wrote:
> On Thu, Sep 12, 2024 at 8:58 AM Joe Damato <jdamato@...tly.com> wrote:
> >
> > Link IRQs to NAPI instances with netif_napi_set_irq. This information
> > can be queried with the netdev-genl API.
> >
> > Compare the output of /proc/interrupts for my tg3 device with the output of
> > netdev-genl after applying this patch:
> >
> > $ cat /proc/interrupts | grep eth0 | cut -f1 --delimiter=':'
> >  331
> >  332
> >  333
> >  334
> >  335
> >
> > $ ./tools/net/ynl/cli.py --spec Documentation/netlink/specs/netdev.yaml \
> >                          --dump napi-get --json='{"ifindex": 2}'
> >
> > [{'id': 149, 'ifindex': 2, 'irq': 335},
> >  {'id': 148, 'ifindex': 2, 'irq': 334},
> >  {'id': 147, 'ifindex': 2, 'irq': 333},
> >  {'id': 146, 'ifindex': 2, 'irq': 332},
> >  {'id': 145, 'ifindex': 2, 'irq': 331}]
> >
> > Signed-off-by: Joe Damato <jdamato@...tly.com>
> > ---
> >  drivers/net/ethernet/broadcom/tg3.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
> > index 378815917741..c187b13ab3e6 100644
> > --- a/drivers/net/ethernet/broadcom/tg3.c
> > +++ b/drivers/net/ethernet/broadcom/tg3.c
> > @@ -7393,6 +7393,14 @@ static int tg3_poll(struct napi_struct *napi, int budget)
> >         return work_done;
> >  }
> >
> > +static void tg3_napi_set_irq(struct tg3 *tp)
> > +{
> > +       int i;
> > +
> > +       for (i = 0; i < tp->irq_cnt; i++)
> > +               netif_napi_set_irq(&tp->napi[i].napi, tp->napi[i].irq_vec);
> 
> Looks good, but why not just add netif_napi_set_irq() to the existing
> loop in tg3_napi_init()?  It will reduce the lines of code a bit.
> Thanks.

I made a separate function because:
  - tg3_napi_init would need two calls (once for i=0, and once in
    the loop), and
  - tg3_napi_init and tg3_napi_enable are separated in the driver,
    so I figured I'd separate the IRQ linking, too.

Can you let me know if you want me to submit a v2 which modifies
tg3_napi_init instead?