Re: [Xen-devel] Reduce CPU Utilization make Network Perfromance better??

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> 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.

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.

> Why not show network throught directly??

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.

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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