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Re: [Xen-devel] I/O descriptor ring size bottleneck?

To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] I/O descriptor ring size bottleneck?
From: Diwaker Gupta <diwakergupta@xxxxxxxxx>
Date: Sun, 20 Mar 2005 16:06:38 -0800
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxxx, ian.pratt@xxxxxxxxxxxx
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Reply-to: Diwaker Gupta <diwakergupta@xxxxxxxxx>
Sender: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx
> BTW, I'd actually be very suspicious of dummynet's ability to operate at
> 500Mb/s. It's possible that the reduced bandwidth is due to some bad
> interaction between burstiness caused by Xen's context switching and
> dummynet.

Could you elaborate a bit more on this? Even if dummynet can't operate
at 500Mbps, we should atleast see the same degradation in performance

> Are your dom0 and domU running on the same processor? Could you try
> using hyperthreading or SMP?

Yep, same processor. For various other reasons, I wanted to avoid SMP,
so I was running with the nosmp option. I'll try running with SMP and
post an update.

> Have you checked that domU <-> domU performance is good on the LAN with
> a single TCP connection?

I had a long time back, but I think that was with SMP. I'll check again. 
Diwaker Gupta

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