From: Yuri Benditovich <yuri.benditovich@daynix.com>
To: Akihiko Odaki <akihiko.odaki@daynix.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
qemu-devel@nongnu.org, Andrew Melnychenko <andrew@daynix.com>
Subject: Re: [PATCH v6 11/21] virtio-net: Return an error when vhost cannot enable RSS
Date: Thu, 2 Nov 2023 11:09:27 +0200 [thread overview]
Message-ID: <CAOEp5OcDMdKKPHSVd-GxT-GkBpvbWkMijSBgwihPsEnxmDR7eA@mail.gmail.com> (raw)
In-Reply-To: <e469b33b-c3f3-4d88-bdf2-508c4a35c827@daynix.com>
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Probably we mix two different patches in this discussion.
Focusing on the patch in the e-mail header:
IMO it is not acceptable to fail QEMU run for one feature that we can't
make active when we silently drop all other features in such a case.
On Wed, Nov 1, 2023 at 11:15 AM Akihiko Odaki <akihiko.odaki@daynix.com>
wrote:
> On 2023/11/01 18:09, Michael S. Tsirkin wrote:
> > On Wed, Nov 01, 2023 at 05:35:50PM +0900, Akihiko Odaki wrote:
> >> On 2023/11/01 15:38, Michael S. Tsirkin wrote:
> >>> On Wed, Nov 01, 2023 at 01:50:00PM +0900, Akihiko Odaki wrote:
> >>>> We had another discussion regarding migration for patch "virtio-net:
> Do not
> >>>> clear VIRTIO_NET_F_HASH_REPORT". It does change the runtime behavior
> so we
> >>>> need to take migration into account. I still think the patch does not
> >>>> require a compatibility flag since it only exposes a new feature and
> does
> >>>> not prevent migrating from old QEMU that exposes less features. It
> instead
> >>>> fixes the case where migrating between hosts with different tap
> feature
> >>>> sets.
> >>>
> >>> When in doubt, add a compat flag.
> >>
> >> Personally I'm confident about the migration compatibility with patch
> >> "virtio-net: Do not clear VIRTIO_NET_F_HASH_REPORT". virtio-net already
> does
> >> the same thing when the tap implementation on the destination implements
> >> virtio-net header support while the counterpart of the source does not.
> >
> > Trust me there's been so many times where we were very sure and
> > problems come up later. Just don't enable new functionality for
> > old machine types, problem solved. Why is this hard?
>
> I see. I'll add a compatibility flag for VIRTIO_NET_F_HASH_REPORT
> exposure; it should be quite easy.
>
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next prev parent reply other threads:[~2023-11-02 9:10 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-30 5:12 [PATCH v6 00/21] virtio-net RSS/hash report fixes and improvements Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 01/21] tap: Remove tap_probe_vnet_hdr_len() Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 02/21] tap: Remove qemu_using_vnet_hdr() Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 03/21] net: Move virtio-net header length assertion Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 04/21] net: Remove receive_raw() Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 05/21] tap: Remove tap_receive() Akihiko Odaki
2023-10-30 18:52 ` Zhang, Chen
2023-10-31 4:57 ` Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 06/21] net: Remove flag propagation Akihiko Odaki
2023-11-10 7:35 ` Pavel Dovgalyuk
2023-11-11 14:27 ` Akihiko Odaki
2023-11-13 8:14 ` Pavel Dovgalyuk
2023-10-30 5:12 ` [PATCH v6 07/21] tap: Shrink zeroed virtio-net header Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 08/21] virtio-net: Copy header only when necessary Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 09/21] virtio-net: Disable RSS on reset Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 10/21] virtio-net: Unify the logic to update NIC state for RSS Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 11/21] virtio-net: Return an error when vhost cannot enable RSS Akihiko Odaki
2023-10-30 12:14 ` Yuri Benditovich
2023-10-30 12:21 ` Akihiko Odaki
2023-10-30 12:51 ` Yuri Benditovich
2023-10-30 13:14 ` Akihiko Odaki
2023-11-01 4:19 ` Jason Wang
2023-11-01 4:50 ` Akihiko Odaki
2023-11-01 6:38 ` Michael S. Tsirkin
2023-11-01 8:35 ` Akihiko Odaki
2023-11-01 9:09 ` Michael S. Tsirkin
2023-11-01 9:15 ` Akihiko Odaki
2023-11-02 9:09 ` Yuri Benditovich [this message]
2023-11-02 9:33 ` Michael S. Tsirkin
2023-11-02 10:20 ` Yuri Benditovich
2023-11-02 11:26 ` Michael S. Tsirkin
2023-11-02 12:00 ` Yuri Benditovich
2023-11-02 13:18 ` Michael S. Tsirkin
2023-11-02 14:56 ` Akihiko Odaki
2023-11-03 9:35 ` Yuri Benditovich
2023-11-03 9:55 ` Akihiko Odaki
2023-11-03 13:14 ` Yuri Benditovich
2023-11-11 15:28 ` Akihiko Odaki
2023-11-13 11:44 ` Yuri Benditovich
2023-11-13 12:44 ` Akihiko Odaki
2023-11-13 17:26 ` Yuri Benditovich
2023-11-14 7:03 ` Akihiko Odaki
2023-11-14 22:09 ` Yuri Benditovich
2023-11-15 6:09 ` Akihiko Odaki
2023-11-16 5:14 ` Jason Wang
2023-10-30 5:12 ` [PATCH v6 12/21] virtio-net: Enable software RSS Akihiko Odaki
2023-10-30 12:42 ` Yuri Benditovich
2023-10-30 5:12 ` [PATCH v6 13/21] virtio-net: Always set populate_hash Akihiko Odaki
2023-10-30 19:02 ` Zhang, Chen
2023-10-31 4:47 ` Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 14/21] virtio-net: Do not write hashes to peer buffer Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 15/21] virtio-net: Do not clear VIRTIO_NET_F_HASH_REPORT Akihiko Odaki
2023-11-03 13:26 ` Yuri Benditovich
2023-10-30 5:12 ` [PATCH v6 16/21] ebpf: Fix RSS error handling Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 17/21] ebpf: Use standard section name Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 18/21] ebpf: Simplify error handling Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 19/21] ebpf: Return 0 when configuration fails Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 20/21] ebpf: Refactor tun_rss_steering_prog() Akihiko Odaki
2023-10-30 5:12 ` [PATCH v6 21/21] ebpf: Add a separate target for skeleton Akihiko Odaki
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