Fwd: [Xen-users] Does Xen 3.3 support giga bit network in the guest?

[Abdul Qadeer <qadeer.qadeer@xxxxxxxxx>]

Forgot to cc to the group.  Sorry John to put this duplicate mail in your inbox.

---------- Forwarded message ----------
From: Abdul Qadeer <qadeer.qadeer@xxxxxxxxx>
Date: Wed, Feb 11, 2009 at 6:24 PM
Subject: Re: [Xen-users] Does Xen 3.3 support giga bit network in the guest?
To: John Haxby <john.haxby@xxxxxxxxxx>

The virtual NIC doesn't limit its speed to 100Mb.   It reports that to the guest OS because it has to report _something_ but it doesn't throttle back to 100Mb.    The only way to find out the actual transfer speed is to measure it -- what you actually get depends on a variety of factors, but not the emulated link speed.

I see.  I tried to do a quick measurement using wget.  There were two guests.  I placed a big fie in one guest and get it from the other guest using wget.  The max speed was about 2.2MBps (i.e. about 16 Mbps).  That is very poor speed indeed and the test was not able to saturate the available bandwidth (i.e 100 Mbps as shown in guest and actually a 1000 Mbps in dom0).  But as you said that there can be many facors (my guess is factors like emulation and the memory subsystem and not to forget that the system is using fully virtualized guests).

So probably I need to use para-virtualized net front drivers to get better througput?

Thanks,
Abdul Qadeer

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