From: Parav Pandit <parav@nvidia.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "virtio-dev@lists.oasis-open.org"
<virtio-dev@lists.oasis-open.org>,
"cohuck@redhat.com" <cohuck@redhat.com>,
"virtio-comment@lists.oasis-open.org"
<virtio-comment@lists.oasis-open.org>,
Shahaf Shuler <shahafs@nvidia.com>
Subject: [virtio-dev] RE: [PATCH 00/11] Introduce transitional mmr pci device
Date: Mon, 3 Apr 2023 15:16:53 +0000 [thread overview]
Message-ID: <PH0PR12MB5481EC65708410304D9C1EA3DC929@PH0PR12MB5481.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20230403110320-mutt-send-email-mst@kernel.org>
> From: Michael S. Tsirkin <mst@redhat.com>
> Sent: Monday, April 3, 2023 11:07 AM
> > > OTOH it is presumably required for scalability anyway, no?
> > No.
> > Most new generation SIOV and SR-IOV devices operate without any para-
> virtualization.
>
> Don't see the connection to PV. You need an emulation layer in the host if you
> want to run legacy guests. Looks like it could do transport vq just as well.
>
Transport vq for legacy MMR purpose seems fine with its latency and DMA overheads.
Your question was about "scalability".
After your latest response, I am unclear what "scalability" means.
Do you mean saving the register space in the PCI device?
If yes, than, no for legacy guests for scalability it is not required, because the legacy register is subset of 1.x.
> > > And presumably it can all be done in firmware ...
> > > Is there actual hardware that can't implement transport vq but is
> > > going to implement the mmr spec?
> > >
> > Nvidia and Marvell DPUs implement MMR spec.
>
> Hmm implement it in what sense exactly?
>
Do not follow the question.
The proposed series will be implemented as PCI SR-IOV devices using MMR spec.
> > Transport VQ has very high latency and DMA overheads for 2 to 4 bytes
> read/write.
>
> How many of these 2 byte accesses trigger from a typical guest?
>
Mostly during the VM boot time. 20 to 40 registers read write access.
> > And before discussing "why not that approach", lets finish reviewing "this
> approach" first.
>
> That's a weird way to put it. We don't want so many ways to do legacy if we can
> help it.
Sure, so lets finish the review of current proposal details.
At the moment
a. I don't see any visible gain of transport VQ other than device reset part I explained.
b. it can be a way with high latency, DMA overheads on the virtqueue for read/writes for small access.
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next prev parent reply other threads:[~2023-04-03 15:17 UTC|newest]
Thread overview: 200+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 22:58 [virtio-dev] [PATCH 00/11] Introduce transitional mmr pci device Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 01/11] transport-pci: Use lowecase alphabets Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 02/11] transport-pci: Move transitional device id to legacy section Parav Pandit
2023-03-31 6:43 ` [virtio-dev] " Michael S. Tsirkin
2023-03-31 21:24 ` [virtio-dev] " Parav Pandit
2023-04-02 7:54 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 14:42 ` [virtio-dev] " Parav Pandit
2023-04-03 14:50 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 14:58 ` [virtio-dev] " Parav Pandit
2023-04-03 15:14 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 03/11] transport-pci: Split notes of PCI Device Layout Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 04/11] transport-pci: Rename and move legacy PCI Device layout section Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 05/11] introduction: Add missing helping verb Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 06/11] introduction: Introduce transitional MMR interface Parav Pandit
2023-04-07 9:17 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 07/11] transport-pci: Introduce transitional MMR device id Parav Pandit
2023-04-04 7:28 ` [virtio-dev] " Michael S. Tsirkin
2023-04-04 16:08 ` Parav Pandit
2023-04-07 12:03 ` [virtio-dev] Re: [virtio-comment] " Michael S. Tsirkin
2023-04-07 15:18 ` [virtio-dev] " Parav Pandit
2023-04-07 15:51 ` [virtio-dev] " Michael S. Tsirkin
2023-04-09 3:15 ` [virtio-dev] " Parav Pandit
2023-04-10 10:18 ` [virtio-dev] " Michael S. Tsirkin
2023-04-10 14:34 ` Parav Pandit
2023-04-10 19:58 ` Michael S. Tsirkin
2023-04-10 20:16 ` Parav Pandit
2023-04-07 8:37 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 08/11] transport-pci: Introduce virtio extended capability Parav Pandit
2023-04-04 7:35 ` [virtio-dev] " Michael S. Tsirkin
2023-04-04 7:54 ` Cornelia Huck
2023-04-04 12:43 ` Michael S. Tsirkin
2023-04-04 13:19 ` Cornelia Huck
2023-04-04 14:37 ` Michael S. Tsirkin
2023-04-10 16:21 ` Parav Pandit
2023-04-10 19:49 ` Michael S. Tsirkin
2023-04-10 19:57 ` [virtio-dev] " Parav Pandit
2023-04-10 20:02 ` [virtio-dev] " Michael S. Tsirkin
2023-04-11 8:39 ` Cornelia Huck
2023-04-04 21:18 ` [virtio-dev] " Parav Pandit
2023-04-05 5:10 ` [virtio-dev] " Michael S. Tsirkin
2023-04-05 13:16 ` [virtio-dev] " Parav Pandit
2023-04-07 8:15 ` [virtio-dev] " Michael S. Tsirkin
2023-04-10 1:36 ` [virtio-dev] " Jason Wang
2023-04-10 6:24 ` Michael S. Tsirkin
2023-04-10 7:16 ` Jason Wang
2023-04-10 10:04 ` Michael S. Tsirkin
2023-04-11 2:19 ` Jason Wang
2023-04-11 7:00 ` Michael S. Tsirkin
2023-04-11 9:07 ` Jason Wang
2023-04-11 10:43 ` Michael S. Tsirkin
2023-04-11 13:59 ` Parav Pandit
2023-04-11 14:11 ` Michael S. Tsirkin
2023-04-11 13:47 ` Parav Pandit
2023-04-11 14:02 ` Michael S. Tsirkin
2023-04-11 14:07 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-11 14:10 ` [virtio-dev] " Michael S. Tsirkin
2023-04-11 14:30 ` [virtio-dev] " Parav Pandit
2023-04-10 17:54 ` Parav Pandit
2023-04-10 17:58 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-11 3:28 ` Jason Wang
2023-04-11 19:01 ` Parav Pandit
2023-04-11 21:25 ` Michael S. Tsirkin
2023-04-12 0:40 ` Parav Pandit
2023-04-12 2:56 ` Michael S. Tsirkin
2023-04-12 4:07 ` Jason Wang
2023-04-12 4:20 ` Michael S. Tsirkin
2023-04-12 4:53 ` [virtio-dev] Re: [virtio-comment] " Jason Wang
2023-04-12 5:25 ` Michael S. Tsirkin
2023-04-12 5:37 ` Jason Wang
2023-04-13 17:03 ` Michael S. Tsirkin
2023-04-12 4:04 ` Jason Wang
2023-04-12 4:13 ` Parav Pandit
2023-04-12 4:20 ` Michael S. Tsirkin
2023-04-12 4:55 ` Jason Wang
2023-05-19 6:10 ` [virtio-dev] " Michael S. Tsirkin
2023-05-19 21:02 ` [virtio-dev] " Parav Pandit
2023-05-21 5:57 ` [virtio-dev] " Michael S. Tsirkin
2023-05-21 13:24 ` [virtio-dev] " Parav Pandit
2023-05-21 14:34 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 09/11] transport-pci: Describe PCI MMR dev config registers Parav Pandit
2023-04-07 8:55 ` [virtio-dev] " Michael S. Tsirkin
2023-04-10 1:33 ` [virtio-dev] Re: [virtio-comment] " Jason Wang
2023-04-10 6:14 ` Michael S. Tsirkin
2023-04-10 6:20 ` Jason Wang
2023-04-10 6:39 ` Michael S. Tsirkin
2023-04-10 7:20 ` Jason Wang
2023-04-10 10:06 ` Michael S. Tsirkin
2023-04-11 2:13 ` Jason Wang
2023-04-11 7:04 ` Michael S. Tsirkin
2023-04-11 9:01 ` Jason Wang
[not found] ` <CALBs2cXURMEzCGnULicXbsBfwnKE5cZOz=M-_hhFCXZ=Lqb9Nw@mail.gmail.com>
2023-04-11 10:39 ` Michael S. Tsirkin
2023-04-11 11:03 ` Yan Vugenfirer
2023-04-11 10:42 ` Michael S. Tsirkin
2023-04-12 3:58 ` Jason Wang
2023-04-12 4:15 ` Michael S. Tsirkin
2023-04-12 4:51 ` Jason Wang
2023-04-12 5:01 ` [virtio-dev] " Parav Pandit
2023-04-12 5:14 ` [virtio-dev] " Jason Wang
2023-04-12 5:30 ` [virtio-dev] " Parav Pandit
2023-04-12 5:38 ` [virtio-dev] " Jason Wang
2023-04-12 5:55 ` [virtio-dev] " Parav Pandit
2023-04-12 6:15 ` [virtio-dev] " Jason Wang
2023-04-12 14:23 ` [virtio-dev] " Parav Pandit
2023-04-13 1:48 ` [virtio-dev] " Jason Wang
2023-04-13 3:31 ` Parav Pandit
2023-04-13 5:14 ` Jason Wang
2023-04-13 17:19 ` Michael S. Tsirkin
2023-04-13 19:39 ` [virtio-dev] " Parav Pandit
2023-04-14 3:09 ` [virtio-dev] " Jason Wang
2023-04-14 3:18 ` [virtio-dev] " Parav Pandit
2023-04-14 3:37 ` [virtio-dev] " Jason Wang
2023-04-14 3:51 ` [virtio-dev] " Parav Pandit
2023-04-14 7:05 ` [virtio-dev] " Michael S. Tsirkin
2023-04-17 3:22 ` Jason Wang
2023-04-17 17:23 ` [virtio-dev] " Parav Pandit
2023-04-17 20:26 ` [virtio-dev] " Michael S. Tsirkin
2023-04-17 20:28 ` [virtio-dev] " Parav Pandit
2023-04-18 0:36 ` [virtio-dev] " Jason Wang
2023-04-18 1:30 ` [virtio-dev] " Parav Pandit
2023-04-18 11:58 ` [virtio-dev] " Michael S. Tsirkin
2023-04-18 12:09 ` [virtio-dev] " Parav Pandit
2023-04-18 12:30 ` [virtio-dev] " Michael S. Tsirkin
2023-04-18 12:36 ` [virtio-dev] " Parav Pandit
2023-04-18 1:01 ` [virtio-dev] " Jason Wang
2023-04-18 1:48 ` [virtio-dev] " Parav Pandit
2023-04-13 17:24 ` [virtio-dev] " Parav Pandit
2023-04-13 21:02 ` Michael S. Tsirkin
2023-04-13 21:08 ` [virtio-dev] " Parav Pandit
2023-04-14 2:36 ` [virtio-dev] " Jason Wang
2023-04-14 2:43 ` [virtio-dev] " Parav Pandit
2023-04-14 6:57 ` [virtio-dev] " Michael S. Tsirkin
2023-04-16 13:41 ` [virtio-dev] " Parav Pandit
2023-04-16 20:44 ` [virtio-dev] " Michael S. Tsirkin
2023-04-17 16:59 ` [virtio-dev] " Parav Pandit
2023-04-18 1:09 ` [virtio-dev] " Jason Wang
2023-04-18 1:37 ` [virtio-dev] " Parav Pandit
2023-04-14 6:58 ` [virtio-dev] " Michael S. Tsirkin
2023-04-14 3:08 ` Jason Wang
2023-04-14 3:13 ` [virtio-dev] " Parav Pandit
2023-04-14 3:18 ` [virtio-dev] " Jason Wang
2023-04-14 3:22 ` [virtio-dev] " Parav Pandit
2023-04-14 3:29 ` [virtio-dev] " Jason Wang
2023-04-11 13:57 ` [virtio-dev] " Parav Pandit
2023-04-12 4:33 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 10/11] transport-pci: Use driver notification PCI capability Parav Pandit
2023-04-12 4:31 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 4:37 ` [virtio-dev] " Parav Pandit
2023-04-12 4:43 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 4:48 ` [virtio-dev] " Parav Pandit
2023-04-12 5:02 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:06 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-12 5:17 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:24 ` [virtio-dev] " Parav Pandit
2023-04-12 5:27 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 11/11] conformance: Add transitional MMR interface conformance Parav Pandit
2023-03-31 7:03 ` [virtio-dev] Re: [PATCH 00/11] Introduce transitional mmr pci device Michael S. Tsirkin
2023-03-31 21:43 ` Parav Pandit
2023-04-03 14:53 ` Michael S. Tsirkin
2023-04-03 14:57 ` [virtio-dev] " Parav Pandit
2023-04-03 15:06 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 15:16 ` Parav Pandit [this message]
2023-04-03 15:23 ` Michael S. Tsirkin
2023-04-03 15:34 ` Michael S. Tsirkin
2023-04-03 15:47 ` [virtio-dev] " Parav Pandit
2023-04-03 17:28 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 17:35 ` Parav Pandit
2023-04-03 17:39 ` Michael S. Tsirkin
2023-04-03 15:36 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-03 17:16 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 17:29 ` Parav Pandit
2023-04-03 18:02 ` Michael S. Tsirkin
2023-04-03 20:25 ` [virtio-dev] " Parav Pandit
2023-04-03 21:04 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 22:00 ` Parav Pandit
2023-04-07 9:35 ` Michael S. Tsirkin
2023-04-10 1:52 ` Jason Wang
2023-04-03 14:45 ` [virtio-dev] Re: [virtio-comment] " Stefan Hajnoczi
2023-04-03 14:53 ` Parav Pandit
2023-04-03 17:48 ` Michael S. Tsirkin
2023-04-03 19:11 ` Stefan Hajnoczi
2023-04-03 20:03 ` Michael S. Tsirkin
2023-04-03 19:48 ` [virtio-dev] " Parav Pandit
2023-04-03 20:02 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 20:42 ` [virtio-dev] " Parav Pandit
2023-04-03 21:14 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 22:08 ` Parav Pandit
2023-04-03 19:10 ` Stefan Hajnoczi
2023-04-03 20:27 ` [virtio-dev] " Parav Pandit
2023-04-04 14:30 ` [virtio-dev] " Stefan Hajnoczi
2023-04-12 4:48 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 4:52 ` [virtio-dev] " Parav Pandit
2023-04-12 5:12 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:15 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-12 5:23 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:39 ` [virtio-dev] " Parav Pandit
2023-04-12 6:02 ` Parav Pandit
2023-04-12 5:10 ` [virtio-dev] " Halil Pasic
2023-04-25 2:42 ` [virtio-dev] " Parav Pandit
2023-05-02 7:17 ` [virtio-dev] Re: [virtio-comment] " David Edmondson
2023-05-02 13:54 ` [virtio-dev] " Parav Pandit
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