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Subject: Re: [PATCH v3 8/8] virtio-net: Describe RSS using receive queue handle
On Wed, Mar 22, 2023 at 02:37:48AM +0000, Parav Pandit wrote: > > > > From: Michael S. Tsirkin <mst@redhat.com> > > Sent: Tuesday, March 21, 2023 6:17 PM > > > > -Field \field{unclassified_queue} contains the 0-based index of -the > > > receive virtqueue to place unclassified packets in. Index 0 corresponds to > > receiveq1. > > > +\begin{lstlisting} > > > +le16 rq_handle; > > > +\end{lstlisting} > > > + > > > +\field{rq_handle} is a receive virtqueue handle. It is calculated as > > > +virtqueue number divided by two. For example a receive virtqueue > > > +handle value of 3 corresponds to virtqueue number 6 maps to receiveq4. > > > + > > > +Field \field{unclassified_queue} contains the receive queue handle > > > +\field{rq_handle} described above. > > > > You dropped *which* queue this refers to. > > > Will add back. > > > And it's still kind of complex and non-standard. E.g. what does \begin{lstlisting} > > le16 rq_handle; > > \end{lstlisting} > > mean exactly? Apparently nothing ... > > > Why nothing, it is referenced further down. > Did you suggest moving before using it? > It was just fine to provide forward reference. because it does not say anything about the contents or the format. just some kind of integer. > > I feel what we keep there is really the virtqueue number itself. > > Just stored in this strage format. > > > > And all this talk about handles kind of seems to add yet another term to learn. > > Where in fact all it is, is just a different way to store vqn. > > > > So my idea was this: we say something like: > > > > > > \field{unclassified_queue} contains the virtqueue number of the receive queue > > to place unclassified packets in. > > \field{indirection_table} contains an array of virtqueue numbers of receive > > queues. > > > Above two lines are clearly confusing where virtqueue number describe in rest of the spec and above doesn't align to same notion. That's true. > So better to say field A contains the rq_handle and > > struct rq_handle { > le16 vqn_16_1: 15; > le16 reserved : 1; > }; > > > Both \field{unclassified_queue} and \field{indirection_table} use the following > > format for the virtqueue numbers: > > \begin{lstlisting} > > struct rss_virtqueue_number { > It is really not any superior in term of cost of learning. > > > le16 vqn_16_1 : 15; /* Bits 16 to 1 of the virtqueue number */ > > le16 reserved : 1; /* Set to 0 */ > I like the structure and reserved bit that enables to claim one bit for some unknown future use. > > } > > \end{lstlisting} > > for example, a value of 3 corresponds to virtqueue number 6 and maps to > > receiveq4. > > > > > > > > and then everywhere else we just say it keeps a vq number, we already > > explained it is using this format once no need to repeat that. > > > I just prefer to rename it to rq_handle ( or at least other than virtqueue number) to distinguish it from rest of the virtqueue number. Well first of all I really want to make it clear it's specific to RSS at least for now. So let's prefix with rss_. Maybe I'm wrong but I feel using up a completely new term for something very specific to RSS is a waste. We won't be able to use handle for something else without confusion. So how about just struct rss_rq { le16 vqn_16_1 : 15; /* Bits 16 to 1 of the virtqueue number */ le16 reserved : 1; /* Set to 0 */ }; hmm? > > WDYT?
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