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xen-devel
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!
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel
>>
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