netdev - Re: Flow Control and Port Mirroring Revisited

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Message-ID: <20110121231149.GI2195@verge.net.au>
Date:	Sat, 22 Jan 2011 10:11:52 +1100
From:	Simon Horman <horms@...ge.net.au>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	Rick Jones <rick.jones2@...com>, Jesse Gross <jesse@...ira.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	virtualization@...ts.linux-foundation.org, dev@...nvswitch.org,
	virtualization@...ts.osdl.org, netdev@...r.kernel.org,
	kvm@...r.kernel.org
Subject: Re: Flow Control and Port Mirroring Revisited

On Fri, Jan 21, 2011 at 11:59:30AM +0200, Michael S. Tsirkin wrote:
> On Thu, Jan 20, 2011 at 05:38:33PM +0900, Simon Horman wrote:
> > [ Trimmed Eric from CC list as vger was complaining that it is too long ]
> > 
> > On Tue, Jan 18, 2011 at 11:41:22AM -0800, Rick Jones wrote:
> > > >So it won't be all that simple to implement well, and before we try,
> > > >I'd like to know whether there are applications that are helped
> > > >by it. For example, we could try to measure latency at various
> > > >pps and see whether the backpressure helps. netperf has -b, -w
> > > >flags which might help these measurements.
> > > 
> > > Those options are enabled when one adds --enable-burst to the
> > > pre-compilation ./configure  of netperf (one doesn't have to
> > > recompile netserver).  However, if one is also looking at latency
> > > statistics via the -j option in the top-of-trunk, or simply at the
> > > histogram with --enable-histogram on the ./configure and a verbosity
> > > level of 2 (global -v 2) then one wants the very top of trunk
> > > netperf from:
> > 
> > Hi,
> > 
> > I have constructed a test where I run an un-paced  UDP_STREAM test in
> > one guest and a paced omni rr test in another guest at the same time.
> 
> Hmm, what is this supposed to measure?  Basically each time you run an
> un-paced UDP_STREAM you get some random load on the network.
> You can't tell what it was exactly, only that it was between
> the send and receive throughput.

Rick mentioned in another email that I messed up my test parameters a bit,
so I will re-run the tests, incorporating his suggestions.

What I was attempting to measure was the effect of an unpaced UDP_STREAM
on the latency of more moderated traffic. Because I am interested in
what effect an abusive guest has on other guests and how that my be
mitigated.

Could you suggest some tests that you feel are more appropriate?

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