From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-987-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 94281985E4D for ; Wed, 11 Dec 2019 16:35:06 +0000 (UTC) Date: Wed, 11 Dec 2019 11:34:57 -0500 From: "Michael S. Tsirkin" Message-ID: <20191211113112-mutt-send-email-mst@kernel.org> References: <20191203183212.1721642-1-yuri.benditovich@daynix.com> <20191203152148-mutt-send-email-mst@kernel.org> <471210655.12237442.1575436801606.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 In-Reply-To: <471210655.12237442.1575436801606.JavaMail.zimbra@redhat.com> Subject: Re: [virtio-comment] Re: [PATCH] virtio-net: define feature of per-packet RSS hash delivery Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline To: Yuri Benditovich Cc: Yuri Benditovich , virtio-comment@lists.oasis-open.org List-ID: On Wed, Dec 04, 2019 at 12:20:01AM -0500, Yuri Benditovich wrote: >=20 >=20 > =E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81= =E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2= =94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94= =81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81= =E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2= =94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94= =81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81= =E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2= =94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94=81=E2=94= =81=E2=94=81=E2=94=81=E2=94=81=E2=94=81 >=20 > From: "Michael S. Tsirkin" > To: "Yuri Benditovich" > Cc: virtio-comment@lists.oasis-open.org > Sent: Tuesday, December 3, 2019 10:25:30 PM > Subject: [virtio-comment] Re: [PATCH] virtio-net: define feature of > per-packet RSS hash delivery >=20 > On Tue, Dec 03, 2019 at 08:32:12PM +0200, Yuri Benditovich wrote: > > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/66 > > Conditional extending of virtio header structure to deliver > > packet's hash and hash type used for calculation. > > > > Signed-off-by: Yuri Benditovich >=20 > Functionally this looks mostly good. But we need to change the > way it's documented slightly. >=20 > Probably, because the RSS patch is not merged yet. >=20 >=20 > > --- > > content.tex | 24 ++++++++++++++++++++++++ > > 1 file changed, 24 insertions(+) > > > > diff --git a/content.tex b/content.tex > > index 01be7df..44975e4 100644 > > --- a/content.tex > > +++ b/content.tex > > @@ -2811,6 +2811,9 @@ \subsection{Feature bits}\label{sec:Device Ty= pes / > Network Device / Feature bits > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through cont= rol > > channel. > > =20 > > +\item[VIRTIO_NET_F_HASH_REPORT(58)] Device can report per-packet h= ash > value > > + and a type of calculated hash > > + > > \item[VIRTIO_NET_F_RSS(60)] Device supports RSS (receive-side scal= ing) > > with Toeplitz hash calculation and configurable hash parameter= s for > receive steering > > =20 > > @@ -2844,6 +2847,8 @@ \subsubsection{Feature bit requirements}\labe= l > {sec:Device Types / Network Device > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR] Requires VIRTIO_NET_F_CTRL_VQ. > > \item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or > VIRTIO_NET_F_HOST_TSO6. > > \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ. > > +\item[VIRTIO_NET_F_HASH_REPORT] Requires VIRTIO_NET_F_RSS. > > + > > \end{description} > > =20 > > \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Ty= pes / > Network Device / Feature bits / Legacy Interface: Feature bits} > > @@ -3071,6 +3076,8 @@ \subsection{Device Operation}\label{sec:Devic= e > Types / Network Device / Device O > > le16 csum_start; > > le16 csum_offset; > > le16 num_buffers; > > + le32 hash_value; (Only if VIRTIO_NET_F_HASH_REPORT negotia= ted) > > + le16 hash_type; (Only if VIRTIO_NET_F_HASH_REPORT negotiat= ed) > > }; > > \end{lstlisting} > > =20 > > @@ -3330,6 +3337,15 @@ \subsubsection{Processing of Incoming Packet= s}\ > label{sec:Device Types / Network > > set: if so, device has validated the packet checksum. > > In case of multiple encapsulated protocols, one level of checksu= ms > > has been validated. > > +\item If VIRTIO_NET_F_HASH_REPORT was negotiated and a device has > calculated > > + a hash for the packet, \field{hash_value} contains calculated ha= sh > value and > > + \field{hash_type} contains exact hash type. > > + > > + If the hash was not calculated, \field{hash_type} contains zero. > > + > > + For defined hash types and their meaning, see \ref{sec:Device Ty= pes / > Network Device / Device configuration layout / RSS}. > > + > > + For the procedure of hash calculation, see \ref{sec:Device Types= / > Network Device / Device Operation / Control Virtqueue / Receive-side > scaling (RSS) / RSS hash types}. > > \end{enumerate} > > =20 > > Additionally, VIRTIO_NET_F_GUEST_CSUM, TSO4, TSO6, UDP and ECN > > @@ -3909,6 +3925,14 @@ \subsubsection{Control Virtqueue}\label{sec:= Device > Types / Network Device / Devi > > \item Else skip IPv6 extension headers and calculate the hash as d= efined > above for IPv6 packet without extension headers > > \end{itemize} > > =20 > > +If VIRTIO_NET_F_HASH_REPORT was negotiated, the device reports > calculated hash information in fields of virtio_net_hdr as follows: > > + > > +Exact hash type is populated in \field{hash_type} > > + > > +Hash value is populated in \field{hash_value} > > + > > +If, due to any reason, the device did not calculate the hash, it s= ets \ > field{hash_type} to zero. > > + > > \drivernormative{\subparagraph}{Setting RSS parameters}{Device Typ= es / > Network Device / Device Operation / Control Virtqueue / Receive-side > scaling (RSS) } > > =20 > > A driver MUST NOT send the VIRTIO_NET_CTRL_MQ_RSS_CONFIG command i= f the > feature VIRTIO_NET_F_RSS has not been negotiated. >=20 >=20 > This is understandably a minimal change, but imho messes things up: > hash calculation is no longer part of RSS so really should be moved > from out of there. >=20 > Please advise why "hash calculation is no longer part of RSS". I might be misunderstanding things. It looks like with this one can enable hash even with a single RX queue. No? >=20 >=20 > So we'd have a chapter for hash calculation, defining hash types > etc. >=20 > A chapter for hash calculation is in previous patch > https://lists.oasis-open.org/archives/virtio-comment/201911/msg00014.html >=20 Can't see it there. Do you mean +\subparagraph{RSS hash types}\label{sec:Device Types / Network Device / De= vice Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash = types} ? Sure, what I am saying it needs to be moved from out of RSS then. >=20 > Then both RSS and the new chapter refer to that. >=20 > Also, I am guessing supported hash types should be valid > in config space with the new feature - isn't that right? >=20 > Yes, of course. So we need to say this in the spec I think. > But this is not related to hash delivery. > Packet hash is calculated according to allowed hash types. > If hash delivery is negotiated, the device reports the calculated hash ty= pe > which is, naturally, one of valid ones. >=20 >=20 >=20 > > -- > > 2.17.2 >=20 >=20 > This publicly archived list offers a means to provide input to the > OASIS Virtual I/O Device (VIRTIO) TC. >=20 > In order to verify user consent to the Feedback License terms and > to minimize spam in the list archive, subscription is required > before posting. >=20 > 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/ >=20 >=20 >=20 This publicly archived list offers a means to provide input to the=0D OASIS Virtual I/O Device (VIRTIO) TC.=0D =0D In order to verify user consent to the Feedback License terms and=0D to minimize spam in the list archive, subscription is required=0D before posting.=0D =0D Subscribe: virtio-comment-subscribe@lists.oasis-open.org=0D Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org=0D List help: virtio-comment-help@lists.oasis-open.org=0D List archive: https://lists.oasis-open.org/archives/virtio-comment/=0D Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf= =0D List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lis= ts=0D Committee: https://www.oasis-open.org/committees/virtio/=0D Join OASIS: https://www.oasis-open.org/join/