From: Paul Brook <paul@codesourcery.com>
To: Anthony Liguori <anthony@codemonkey.ws>
Cc: quintela@redhat.com, Marcelo Tosatti <mtosatti@redhat.com>,
qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
kraxel@redhat.com, amit.shah@redhat.com
Subject: Re: [Qemu-devel] Re: [PATCHv2 10/12] tap: add vhost/vhostfd options
Date: Wed, 3 Mar 2010 14:43:29 +0000 [thread overview]
Message-ID: <201003031443.30218.paul@codesourcery.com> (raw)
In-Reply-To: <4B8E6EF3.5020605@codemonkey.ws>
> > That sounds like it's likely to come back and bite you. The guest has no
> > idea which areas of ram happen to be contiguous on the host.
>
> Practically speaking, with target-i386 anything that is contiguous in
> guest physical memory is contiguous in the host address space provided
> it's ram.
>
> These assumptions are important. I have a local branch (that I'll send
> out soon) that implements a ram API and converted virtio to make use of
> it. I'm seeing a ~50% increase in tx throughput.
IMO supporting discontiguous regions is a requirement. target-i386 might get
away with contiguous memory, because it omits most of the board level details.
For everything else I'd expect this to be a real problem.
I'm not happy about the not-remapable assumption either. In my experience
this is fairly common. In fact many real x86 machines have this capability
(to workaround the 4G PCI hole).
By my reading the ppc440_bamboo board fails both your assumptions.
I imagine the KVM-PPC folks would be upset if you decided that virtio no
longer worked on this board.
This is all somewhat disappointing, given virtio is supposed to be a DMA based
architecture, and not rely on shared memory semantics.
Paul
next prev parent reply other threads:[~2010-03-03 14:43 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-25 18:27 [Qemu-devel] [PATCHv2 00/12] vhost-net: upstream integration Michael S. Tsirkin
2010-02-25 18:27 ` [Qemu-devel] [PATCHv2 05/12] virtio: add APIs for queue fields Michael S. Tsirkin
2010-02-25 18:49 ` Blue Swirl
2010-02-26 14:53 ` Michael S. Tsirkin
2010-02-25 19:25 ` [Qemu-devel] " Anthony Liguori
2010-02-26 8:46 ` Gleb Natapov
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 09/12] vhost: vhost net support Michael S. Tsirkin
2010-02-25 19:04 ` [Qemu-devel] " Juan Quintela
2010-02-26 14:32 ` Michael S. Tsirkin
2010-02-26 14:38 ` Anthony Liguori
2010-02-26 14:54 ` Michael S. Tsirkin
2010-02-25 19:44 ` Anthony Liguori
2010-02-26 14:49 ` Michael S. Tsirkin
2010-02-26 15:18 ` Anthony Liguori
2010-02-27 19:38 ` Michael S. Tsirkin
2010-02-28 1:59 ` Paul Brook
2010-02-28 10:15 ` Michael S. Tsirkin
2010-02-28 12:45 ` Paul Brook
2010-02-28 14:44 ` Michael S. Tsirkin
2010-02-28 15:23 ` Paul Brook
2010-02-28 15:37 ` Michael S. Tsirkin
2010-02-28 16:02 ` Anthony Liguori
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 02/12] kvm: add API to set ioeventfd Michael S. Tsirkin
2010-02-25 19:19 ` [Qemu-devel] " Anthony Liguori
2010-03-02 17:41 ` Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 04/12] virtio: add notifier support Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 01/12] tap: add interface to get device fd Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 07/12] virtio: move typedef to qemu-common Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 10/12] tap: add vhost/vhostfd options Michael S. Tsirkin
2010-02-25 19:47 ` [Qemu-devel] " Anthony Liguori
2010-02-26 14:51 ` Michael S. Tsirkin
2010-02-26 15:23 ` Anthony Liguori
2010-02-27 19:44 ` Michael S. Tsirkin
2010-02-28 16:08 ` Anthony Liguori
2010-02-28 17:19 ` Michael S. Tsirkin
2010-02-28 20:57 ` Anthony Liguori
2010-02-28 21:01 ` Michael S. Tsirkin
2010-02-28 22:38 ` Anthony Liguori
2010-02-28 22:39 ` Paul Brook
2010-03-01 19:27 ` Michael S. Tsirkin
2010-03-01 21:54 ` Anthony Liguori
2010-03-02 9:57 ` Michael S. Tsirkin
2010-03-02 14:07 ` Anthony Liguori
2010-03-02 14:33 ` Paul Brook
2010-03-02 14:39 ` Anthony Liguori
2010-03-02 14:55 ` Paul Brook
2010-03-02 15:33 ` Anthony Liguori
2010-03-02 15:53 ` Paul Brook
2010-03-02 15:56 ` Michael S. Tsirkin
2010-03-02 16:12 ` Anthony Liguori
2010-03-02 16:21 ` Marcelo Tosatti
2010-03-02 16:12 ` Marcelo Tosatti
2010-03-02 16:56 ` Anthony Liguori
2010-03-02 17:00 ` Michael S. Tsirkin
2010-03-02 18:00 ` Marcelo Tosatti
2010-03-02 18:13 ` Anthony Liguori
2010-03-02 22:41 ` Paul Brook
2010-03-03 14:15 ` Anthony Liguori
2010-03-03 14:43 ` Paul Brook [this message]
2010-03-03 16:24 ` Marcelo Tosatti
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 11/12] tap: add API to retrieve vhost net header Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 06/12] virtio: add set_status callback Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 08/12] virtio-pci: fill in notifier support Michael S. Tsirkin
2010-02-25 19:30 ` [Qemu-devel] " Anthony Liguori
2010-02-28 20:02 ` Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 03/12] notifier: event notifier implementation Michael S. Tsirkin
2010-02-25 19:22 ` [Qemu-devel] " Anthony Liguori
2010-02-28 19:59 ` Michael S. Tsirkin
2010-02-25 18:28 ` [Qemu-devel] [PATCHv2 12/12] virtio-net: vhost net support Michael S. Tsirkin
2010-02-25 19:49 ` [Qemu-devel] Re: [PATCHv2 00/12] vhost-net: upstream integration Anthony Liguori
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=201003031443.30218.paul@codesourcery.com \
--to=paul@codesourcery.com \
--cc=amit.shah@redhat.com \
--cc=anthony@codemonkey.ws \
--cc=kraxel@redhat.com \
--cc=mst@redhat.com \
--cc=mtosatti@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=quintela@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).