[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: Re: [PATCH v14 10/11] virtio-net: Describe RSS using rss rq id
On Mon, Apr 24, 2023 at 03:22:21PM +0200, Halil Pasic wrote: > On Wed, 19 Apr 2023 04:46:38 +0300 > Parav Pandit <parav@nvidia.com> wrote: > > > The content of the indirection table and unclassified_queue were > > originally described based on mathematical operations. In order to > > make it easier to understand and to avoid intermixing the array > > index with the vq index, introduce a structure > > rss_rq_id (RSS receive queue > > ID) and use it to describe the unclassified_queue and > > indirection_table fields. > > > > As part of it, have the example that uses non-zero virtqueue > > index which helps to have better mapping between receiveX > > object with virtqueue index and the actual value in the > > indirection table. > > > > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163 > > Signed-off-by: Parav Pandit <parav@nvidia.com> > > > > --- > > changelog: > > v12->v13: > > - rename vqn to vq_index > > - renamed vq index to virtqueue index > > v11->v12: > > - use 'virtqueue index' instead of 'virtqueue number' > > v10->v11: > > - commit log updated to drop old reference to rq_handle, replaced with > > rss_rq_id detail > > v8->v9: > > - reword rss_rq_id and unclassified_packets description > > - use article > > - use 'vq number' instead of 'virtqueue number' > > v4->v5: > > - change subject to reflect rss_rq_id > > - fixed accidental removal of "unclassifed packets". > > - simplfied text around indirection_table mask to use the term > > destination receive virtqueue. This aligns with next line about queue > > reset. > > - removed rss_rq_id references as indirection table and > > unclassified_queue data type is self explanatory > > v3->v4: > > - renamed rq_handle to rss_rq_id > > - moved rss_rq_id definition close to its usage in rss_config struct > > v2->v3: > > - moved rq_handle definition before using it > > - removed duplicate example as rq_handle is now described first > > v0->v1: > > - new patch suggested by Michael Tsirkin > > --- > > device-types/net/description.tex | 27 ++++++++++++++++++++------- > > 1 file changed, 20 insertions(+), 7 deletions(-) > > > > diff --git a/device-types/net/description.tex b/device-types/net/description.tex > > index f3f9f1d..e4d236e 100644 > > --- a/device-types/net/description.tex > > +++ b/device-types/net/description.tex > > @@ -1434,11 +1434,16 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > > > > Driver sends a VIRTIO_NET_CTRL_MQ_RSS_CONFIG command maybe add: including virtqueue index of relevant receive queues > using the following format for \field{command-specific-data}: > > \begin{lstlisting} > > +struct rss_rq_id { > > + le16 vq_index_1_16: 15; /* Bits 1 to 16 of the virtqueue index */ > > + le16 reserved: 1; /* Set to zero */ > > +}; > > + > > I'm not a fan of this being done with bitmaps, as I have stated before, > but I can live with it. Same. > > struct virtio_net_rss_config { > > le32 hash_types; > > le16 indirection_table_mask; > > - le16 unclassified_queue; > > - le16 indirection_table[indirection_table_length]; > > + struct rss_rq_id unclassified_queue; > > + struct rss_rq_id indirection_table[indirection_table_length]; > > le16 max_tx_vq; > > u8 hash_key_length; > > u8 hash_key_data[hash_key_length]; > > @@ -1453,10 +1458,15 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > > \field{indirection_table} array. > > Number of entries in \field{indirection_table} is (\field{indirection_table_mask} + 1). > > > > -Field \field{unclassified_queue} contains the 0-based index of > > -the receive virtqueue to place unclassified packets in. Index 0 corresponds to receiveq1. > > +\field{rss_rq_id} is a receive virtqueue id. \field{vq_index_1_16} > > +consists of bits 1 to 16 of a virtqueue index. For example, a > > +\field{vq_index_1_16} value of 3 corresponds to virtqueue index 6, > > +which maps to receiveq4. > > + > > +Field \field{unclassified_queue} contains the receive virtqueue > > +in which to place unclassified packets. > > It does not contain a receive virtqueue but its \field{rss_rq_id}, > i.e. it's "receive virtqueue id". Yes all this last chunk is not an improvement. My whole point was that we do not need a name for this thing that is struct rss_rq_id. It's just a weird way to store a vq index. Also \field{rss_rq_id} is confusing since it's actually \field{struct rss_rq_id}. We are using C-like not C++ like syntax ;) One way to address all this: \field{struct rss_rq_id} contains a virtqueue index: \field{vq_index_1_16} consists of bits 1 to 16 of a virtqueue index. For example, a \field{vq_index_1_16} value of 3 corresponds to virtqueue index 6, which maps to receiveq4. Field \field{unclassified_queue} contains the virtqueue index of the receive virtqueue to place unclassified packets in, in \field{struct rss_rq_id} format. > > +\field{vq_index_1_16} value of 3 corresponds to virtqueue index 6, > > +which maps to receiveq4. > > + > > +Field \field{unclassified_queue} contains the receive virtqueue > > +in which to place unclassified packets. > > > > -Field \field{indirection_table} contains an array of 0-based indices of receive virtqueues. Index 0 corresponds to receiveq1. > > +Field \field{indirection_table} is an array of receive virtqueues. > > Same here. > > > > > A driver sets \field{max_tx_vq} to inform a device how many transmit virtqueues it may use (transmitq1\ldots transmitq \field{max_tx_vq}). > > > > @@ -1466,7 +1476,8 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > > > > A driver MUST NOT send the VIRTIO_NET_CTRL_MQ_RSS_CONFIG command if the feature VIRTIO_NET_F_RSS has not been negotiated. > > > > -A driver MUST fill the \field{indirection_table} array only with indices of enabled queues. Index 0 corresponds to receiveq1. > > +A driver MUST fill the \field{indirection_table} array only with > > +enabled receive virtqueues. > > Same here. > > > > The number of entries in \field{indirection_table} (\field{indirection_table_mask} + 1) MUST be a power of two. > > > > @@ -1479,7 +1490,9 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > > \begin{itemize} > > \item Calculate the hash of the packet as defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets}. > > \item If the device did not calculate the hash for the specific packet, the device directs the packet to the receiveq specified by \field{unclassified_queue} of virtio_net_rss_config structure. > > -\item Apply \field{indirection_table_mask} to the calculated hash and use the result as the index in the indirection table to get 0-based number of destination receiveq. > > +\item Apply \field{indirection_table_mask} to the calculated hash > > +and use the result as the index in the indirection table to get > > +the destination receive virtqueue. > > Same here. > > > \item If the destination receive queue is being reset (See \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}), the device MUST drop the packet. > > \end{itemize} > >
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]