netdev - Re: [PATCH net-next] sfc: The size of the RX recycle ring should be more flexible

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Message-ID: <20220112090843.qm27ofgtdz7ouuxw@gmail.com>
Date:   Wed, 12 Jan 2022 09:08:43 +0000
From:   Martin Habets <habetsm.xilinx@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Íñigo Huguet <ihuguet@...hat.com>,
        davem@...emloft.net, ecree.xilinx@...il.com,
        netdev@...r.kernel.org, dinang@...inx.com
Subject: Re: [PATCH net-next] sfc: The size of the RX recycle ring should be
 more flexible

On Mon, Jan 10, 2022 at 09:22:24AM -0800, Jakub Kicinski wrote:
> On Mon, 10 Jan 2022 08:58:21 +0000 Martin Habets wrote:
> > +static unsigned int efx_ef10_recycle_ring_size(const struct efx_nic *efx)
> > +{
> > +	unsigned int ret;
> > +
> > +	/* There is no difference between PFs and VFs. The side is based on
> > +	 * the maximum link speed of a given NIC.
> > +	 */
> > +	switch (efx->pci_dev->device & 0xfff) {
> > +	case 0x0903:	/* Farmingdale can do up to 10G */
> > +#ifdef CONFIG_PPC64
> > +		ret = 4 * EFX_RECYCLE_RING_SIZE_10G;
> > +#else
> > +		ret = EFX_RECYCLE_RING_SIZE_10G;
> > +#endif
> > +		break;
> > +	case 0x0923:	/* Greenport can do up to 40G */
> > +	case 0x0a03:	/* Medford can do up to 40G */
> > +#ifdef CONFIG_PPC64
> > +		ret = 16 * EFX_RECYCLE_RING_SIZE_10G;
> > +#else
> > +		ret = 4 * EFX_RECYCLE_RING_SIZE_10G;
> > +#endif
> > +		break;
> > +	default:	/* Medford2 can do up to 100G */
> > +		ret = 10 * EFX_RECYCLE_RING_SIZE_10G;
> > +	}
> > +	return ret;
> > +}
> 
> Why not factor out the 4x scaling for powerpc outside of the switch?
> 
> The callback could return the scaling factor but failing that:
> 
> static unsigned int efx_ef10_recycle_ring_size(const struct efx_nic *efx)
> {
> 	unsigned int ret = EFX_RECYCLE_RING_SIZE_10G;;
> 
> 	/* There is no difference between PFs and VFs. The side is based on
> 	 * the maximum link speed of a given NIC.
> 	 */
> 	switch (efx->pci_dev->device & 0xfff) {
> 	case 0x0903:	/* Farmingdale can do up to 10G */
> 		break;
> 	case 0x0923:	/* Greenport can do up to 40G */
> 	case 0x0a03:	/* Medford can do up to 40G */
> 		ret *= 4;
> 		break;
> 	default:	/* Medford2 can do up to 100G */
> 		ret *= 10;
> 	}
> 
> 	if (IS_ENABLED(CONFIG_PPC64))
> 		ret *= 4;
> 
> 	return ret;
> }

Thanks, will do.

> Other than that - net-next is closed, please switch to RFC postings
> until it opens back up once 5.17-rc1 is cut. Thanks!

I knew it had to be near closing, I even checked the weblink. ;)
Will repost when net-next is open again.

Martin