Thanks for reply.
It's really helpful to realize the reason about reducing CPU utilization.
And it is told me that, Xen and Native Linux achive line rate under 1 Gps is
truth.
Same as experimental I've done shows.
I perhaps need to obtain bandwith within 10 Gbps to make deference between
Xen and Native Linux.
Sincerely,
Brian Fang
----- Original Message -----
From: "Santos, Jose Renato G" <joserenato.santos@xxxxxx>
To: "Mark Williamson" <mark.williamson@xxxxxxxxxxxx>;
<xen-devel@xxxxxxxxxxxxxxxxxxx>
Cc: "Brian Fang" <m9429015@xxxxxxxxxxxxxxxxx>
Sent: Tuesday, October 09, 2007 1:57 AM
Subject: RE: [Xen-devel] Reduce CPU Utilization make Network
Perfromancebetter??
Just adding a few comments to Mark's reply
-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
Mark Williamson
Sent: Sunday, October 07, 2007 8:22 PM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: Brian Fang
Subject: Re: [Xen-devel] Reduce CPU Utilization make Network
Perfromancebetter??
> I don't know if the guess condition is wright.
> But I still not figure out how the improvement benefit
network throughput.
> Is it because lower CPU utilization higher packet process rate??
Presumably because the CPU processing required to interact
with the network can becomes a bottleneck; therefore
improving the CPU efficiency should increase the throughput.
It's been a long time since I read that paper, but when we
did the first driver domains benchmarks in 2004 we were
burning up a significant fraction of the CPU bandwidth of a
2-way Xeon in order to achieve line rate on gigabit ethernet.
Yes, for gigabit NICs both Xen and linux can achieve
line rate with modern machines
As we move to 10Gb/s NICs the CPU will become the bottleneck,
thus reducing the CPU cost should enable Xen to get better
network throughput.
Also, improving the CPU utilisation encountered in the
course of network processing should make more CPU time
available to other work, which would be good.
Right! Domains do more than just networking. Freeing cycles
from the network stack should improve application performance.
While the experiments are done using a micro network
benchamark (netperf), real applications will have to do real
work in addition to network processing.
> Why not show network throught directly??
Because it is not interesting. Both Xen and linux can
saturate a 1 Gb/s NIC and thus achieve the same
throughput.
Presumably in the case of this paper the goal was to
illustrate the kind of measurements that Xenoprof can make
and the improvements in those measurements that can be
achieved with targetted modifications to the codebase.
Actually the goal is to improve efficiency of Xen networking,
to free cycles for the application and to scale to higher
network bandwidth (i.e. 10 Gb/s)
I agree it would have been interesting to see what effects
on the network throughput were but I guess these would vary
between different machines and network loads in any case.
Just my two cents ;-)
Cheers,
Mark
--
Dave: Just a question. What use is a unicyle with no seat?
And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!
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