[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] unix sockets for qemu
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] unix sockets for qemu |
Date: |
Tue, 26 Feb 2013 16:51:41 +0000 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Feb 26, 2013 at 05:31:04PM +0100, Stefan Hajnoczi wrote:
> On Mon, Feb 25, 2013 at 07:02:30PM -0600, address@hidden wrote:
> > The associated file contains a README that will guide you through the
> > experiment that shows the difference between unix socket carried pings:
> > 0.7ms and inet carried pings: 40ms!!!
>
> There is no fundamental reason for inet sockets to have a 40 millisecond
> round-trip time on localhost. I remember from years ago that Solaris
> "fuses" localhost inet sockets and bypasses TCP for them.
>
> Adding a call to socket_set_nodelay() net/socket.c might help.
Yes, I'm pretty sure it will be the nagle algorithm that is causing this
delay. Localhost IP sockets can round-trip ICMP packets in <0.1 ms
If we don't want to disable nagle by default here, we could at least
make it a configurable option for people.
Regards,
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|