RE: [Xen-devel] what's maximum speed setting for xen network?

["Santos, Jose Renato G (Jose Renato Santos)" <joserenato.santos@xxxxxx>]

  Nivedita,

  Yes, I am working to get oprofile in xen-unstable.
  I was only able to spend a few  hours on this
  My own port to xen-unstable shows the same behavior as 
  the one done by Andrew Theurer.
  I will start debugging xenoprof this week to nail down 
  the problem. 
  Renato

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Nivedita Singhvi
> Sent: Saturday, April 23, 2005 10:37 AM
> To: Keir Fraser
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; zhaoxin@xxxxxxxxxxxxxx; 
> mukesh agrawal
> Subject: Re: [Xen-devel] what's maximum speed setting for xen network?
> 
> 
> Keir Fraser wrote:
> > 
> > On 22 Apr 2005, at 20:53, mukesh agrawal wrote:
> > 
> >> I've got a configuration with DomU talking to Dom0 over a vif, and
> >> seem to be seeing UDP losses, even at low data rates. (I 
> haven't dug 
> >> into this deeply to very the problem yet, though.) So I'd be 
> >> interested if you're seeing something similar.
> > 
> > 
> > We have no back-pressure / flow control on inter-domain networking. 
> > This
> > leads to embarrassing performance for UDP when the sender 
> and receiver 
> > share a CPU. The sender fills the receiver's buffers but 
> continues to 
> > send even though he drops further packets (no buffer space 
> at receiver) 
> > -- then the receiver gets a time slice, receives a ring's worth of 
> > packets -- then the sender gets to run for another time 
> slice, most of 
> > which again is wasted -- and so on.
> > 
> > We need a sensible mechanism for ensuring batched packet 
> delivery, but
> > also to ensure that comms rings do not so easily get 
> overflowed. This 
> > would vastly improve the inter-domain performance, far more than 
> > striving for zero copy or other such tweaks.
> > 
> > It would be great if someone else is interested in 
> investigating this. 
> > :-)
> 
> Hi Keir,
> 
> Yep, I'm one of the people at least looking into this, don't 
> know if others are too :). Thrown some instrumentation in and 
> doing some testing as we speak. Really needed some profiling 
> so was trying to get the oprofile stuff to work in unstable. 
> From what I saw from his last post, Jose is working on it.
> 
> A few people have kindly agreed to do some testing for me too.
> 
> We'll throw some stuff out on the list after the weekend.  I 
> am tracking all the reports of poor networking performance so 
> if people do see some issues please continue to post on the list..
> 
> thanks,
> Nivedita
> 
> 
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