From: Paolo Abeni <pabeni@redhat.com>
To: Jason Wang <jasowang@redhat.com>,
mst@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com,
andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org
Cc: virtualization@lists.linux.dev, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH net] virtio_net: fix alignment for virtio_net_hdr_v1_hash
Date: Wed, 29 Oct 2025 09:19:57 +0100 [thread overview]
Message-ID: <d0f1f8f5-8edf-4409-a3ee-376828f85618@redhat.com> (raw)
In-Reply-To: <20251029012434.75576-1-jasowang@redhat.com>
On 10/29/25 2:24 AM, Jason Wang wrote:
> From: "Michael S. Tsirkin" <mst@redhat.com>
>
> Changing alignment of header would mean it's no longer safe to cast a
> 2 byte aligned pointer between formats. Use two 16 bit fields to make
> it 2 byte aligned as previously.
>
> This fixes the performance regression since
> commit ("virtio_net: enable gso over UDP tunnel support.") as it uses
> virtio_net_hdr_v1_hash_tunnel which embeds
> virtio_net_hdr_v1_hash. Pktgen in guest + XDP_DROP on TAP + vhost_net
> shows the TX PPS is recovered from 2.4Mpps to 4.45Mpps.
>
> Fixes: 56a06bd40fab ("virtio_net: enable gso over UDP tunnel support.")
> Cc: stable@vger.kernel.org
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
Whoops, I replied to the older thread before reading this one.
Acked-by: Paolo Abeni <pabeni@redhat.com>
next prev parent reply other threads:[~2025-10-29 8:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-29 1:24 [PATCH net] virtio_net: fix alignment for virtio_net_hdr_v1_hash Jason Wang
2025-10-29 8:19 ` Paolo Abeni [this message]
2025-10-30 2:40 ` Jason Wang
2025-10-30 8:17 ` Michael S. Tsirkin
2025-10-29 12:49 ` kernel test robot
2025-10-29 15:35 ` kernel test robot
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