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Subject: Re: [virtio-comment] [PATCH v2] virtio-net: Define per-packet hash reporting feature
----- Original Message ----- > From: "Michael S. Tsirkin" <mst@redhat.com> > To: "Yuri Benditovich" <ybendito@redhat.com> > Cc: "Yuri Benditovich" <yuri.benditovich@daynix.com>, > virtio-comment@lists.oasis-open.org > Sent: Monday, February 3, 2020 3:20:56 PM > Subject: Re: [virtio-comment] [PATCH v2] virtio-net: Define per-packet hash > reporting feature > On Mon, Feb 03, 2020 at 08:10:57AM -0500, Yuri Benditovich wrote: > > > > +\item The device uses \field{hash_key_data} of the > > > > virtio_net_rss_config > > > > structure. > > > > +\end{itemize} > > > > +See the definition of virtio_net_rss_config structure in > > > > \ref{sec:Device > > > > Types / Network Device / Device Operation / Control Virtqueue / > > > > Receive-side scaling (RSS) / Setting RSS parameters} > > > > + > > > > +If the feature VIRTIO_NET_F_RSS was not negotiated, the device uses > > > > internal configuration > > > > +of enabled hash types and a key used for hash calculation. > > > > > I don't understand this last paragraph. Could you clarify? > > > > In order to calculate a hash the device shall have 2 things: > > a key for hash calculation > > a bitmask which hash types are enabled > > > > In case the device supportes RSS command (even with single queue), it can > > take them from current RSS configuration. > > If only VIRTIO_NET_F_HASH_REPORT is negotiated, the device uses internal > > preset of both parameters. > > > > Do you suggest something different? > Hmm control over key/mask would be nice to have. > I guess we could add a command along the lines of: > struct virtio_net_hash_config { > le32 hash_types; > le16 reserved[4]; > u8 hash_key_length; > u8 hash_key_data[hash_key_length]; > }; > This needs some thought: we don't want to request that devices have > double the machinery so the command should not be there if RSS is > enabled ... > Maybe the command is only valid if HASH is set but RSS is clear? No problem. To avoid further ping-pongs: What is this reserved[4] needed for? Please confirm: - this is an additional command under VIRTIO_NET_CTRL_MQ - should be supported when HASH_REPORT is negotiated, with or without MQ, not needed if RSS supported - Initially all hashes are disabled > -- > MST > This publicly archived list offers a means to provide input to the > OASIS Virtual I/O Device (VIRTIO) TC. > In order to verify user consent to the Feedback License terms and > to minimize spam in the list archive, subscription is required > before posting. > Subscribe: virtio-comment-subscribe@lists.oasis-open.org > Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org > List help: virtio-comment-help@lists.oasis-open.org > List archive: https://lists.oasis-open.org/archives/virtio-comment/ > Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf > List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists > Committee: https://www.oasis-open.org/committees/virtio/ > Join OASIS: https://www.oasis-open.org/join/
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