qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: Jamie Lokier <jamie@shareable.org>
To: Scott Tsai <scottt.tw@gmail.com>
Cc: qemu-devel@nongnu.org, Paul Brook <paul@codesourcery.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] Re: [PATCH] qemu/virtio: make wmb compiler barrier + comments
Date: Fri, 13 Nov 2009 03:00:03 +0000	[thread overview]
Message-ID: <20091113030003.GE19405@shareable.org> (raw)
In-Reply-To: <ef2f888d0911110918g2c30aba6y765461d2c1737baf@mail.gmail.com>

Scott Tsai wrote:
> I do have a newbie question, when exactly would vrtio have to handle
> concurrent access from multiple threads?
> My current reading of the code suggests:
> 1. when CONFIG_IOTHREAD is true
> 2. when CONFIG_KVM is true and the guest machine has multiple CPUs

It's enough to have CONFIG_KVM with a single guest CPU, isn't it?

Because the guest CPU can still run concurrently with the I/O thread
on kvm, and the host may have multiple CPUs even though the guest does
not.

-- Jamie

  parent reply	other threads:[~2009-11-13  3:00 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-10-26 13:17 [Qemu-devel] [PATCH] qemu/virtio: make wmb compiler barrier + comments Michael S. Tsirkin
2009-11-11  1:34 ` Paul Brook
2009-11-11  9:37   ` [Qemu-devel] " Michael S. Tsirkin
2009-11-11 13:01     ` Paul Brook
2009-11-11 13:12       ` Michael S. Tsirkin
2009-11-11 13:45         ` Paul Brook
2009-11-11 14:08           ` Michael S. Tsirkin
2009-11-11 14:16             ` Paul Brook
2009-11-11 14:34               ` Michael S. Tsirkin
2009-11-11 16:13                 ` Paul Brook
2009-11-11 17:18             ` Scott Tsai
2009-11-11 18:08               ` Michael S. Tsirkin
2009-11-11 18:09               ` Michael S. Tsirkin
2009-11-11 18:37                 ` Scott Tsai
2009-11-11 19:56                   ` Michael S. Tsirkin
2009-11-13  3:00               ` Jamie Lokier [this message]
2009-11-11 13:15       ` Michael S. Tsirkin

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=20091113030003.GE19405@shareable.org \
    --to=jamie@shareable.org \
    --cc=mst@redhat.com \
    --cc=paul@codesourcery.com \
    --cc=qemu-devel@nongnu.org \
    --cc=scottt.tw@gmail.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).