From: Willem de Bruijn <willemdebruijn.kernel@gmail•com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail•com>,
Eric Dumazet <edumazet@google•com>,
Jakub Kicinski <kuba@kernel•org>
Cc: Srujana Challa <schalla@marvell•com>,
Willem de Bruijn <willemb@google•com>,
netdev@vger•kernel.org, virtualization@lists•linux.dev,
pabeni@redhat•com, mst@redhat•com, jasowang@redhat•com,
xuanzhuo@linux•alibaba.com, eperezma@redhat•com,
andrew+netdev@lunn•ch, davem@davemloft•net,
ndabilpuram@marvell•com,
Willem de Bruijn <willemdebruijn.kernel@gmail•com>
Subject: Re: [PATCH net-next] virtio_net: Increase RSS max key size to match NETDEV_RSS_KEY_LEN
Date: Thu, 22 Jan 2026 14:42:57 -0500 [thread overview]
Message-ID: <willemdebruijn.kernel.359531d88f721@gmail.com> (raw)
In-Reply-To: <willemdebruijn.kernel.113a625cf37a9@gmail.com>
Willem de Bruijn wrote:
> Eric Dumazet wrote:
> > On Thu, Jan 22, 2026 at 4:52 PM Jakub Kicinski <kuba@kernel•org> wrote:
> > >
> > > On Thu, 22 Jan 2026 14:45:27 +0530 Srujana Challa wrote:
> > > > Increase VIRTIO_NET_RSS_MAX_KEY_SIZE from 40 to 52 bytes to align with
> > > > the kernel's standard RSS key length defined by NETDEV_RSS_KEY_LEN.
> > >
> > > I've been meaning to bump NETDEV_RSS_KEY_LEN to 128 or some such.
> > > Most modern drivers can't use netdev_rss_key_fill() either because
> > > core generates a tiny key. And the devices support hashing over two
> > > layers of IPv6 for tunnels.
> >
> > Seems fine to me. Back in 2014, RSS was limited to 52 bytes on all known NIC.
>
> What is the purpose of extending?
>
> The current length is sufficient for standard Toeplitz 4-tuple hashing.
Never mind, I should read better:
> And the devices support hashing over two layers of IPv6 for tunnels.
I'm hard pressed to see over 128 B of entropy. But if extending, might
as well go to 256 B right away.
next prev parent reply other threads:[~2026-01-22 19:43 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-22 9:15 [PATCH net-next] virtio_net: Increase RSS max key size to match NETDEV_RSS_KEY_LEN Srujana Challa
2026-01-22 10:15 ` Michael S. Tsirkin
2026-01-23 11:37 ` [EXTERNAL] " Srujana Challa
2026-01-22 15:52 ` Jakub Kicinski
2026-01-22 16:13 ` Eric Dumazet
2026-01-22 16:17 ` Eric Dumazet
2026-01-22 16:52 ` Jakub Kicinski
2026-01-22 19:32 ` Willem de Bruijn
2026-01-22 19:42 ` Willem de Bruijn [this message]
2026-01-23 11:46 ` [EXTERNAL] " Srujana Challa
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