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Re: [Qemu-devel] yet another proposed solution for gcc 4.x


From: Paul Brook
Subject: Re: [Qemu-devel] yet another proposed solution for gcc 4.x
Date: Mon, 5 Jun 2006 14:49:03 +0100
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(everything compiled with gcc3)
> user    0m0.250s
> 9.44444
(everything compiled with gcc4)
> user    0m0.284s
> 9.25806

Your comparison is not valid. You should only change one variable at once.
We don't care whether a gcc4 sha1 is faster or slower than gcc3 sha1. By your 
own numbers gcc4 is slower in absolute terms. We only care whether qemu goes 
faster or slower when running the same binary.

You should also state how any runs you did and what the variation is. 
Especially on modern systems there can be a lot of variation between 
successive runs.

> PS. is there any "standard" way to benchmark qemu that is all agreed upon as
> authoritative other than `make speed`?

Not really. Also, simple benchmarks (which tend to be dominated by a 
single "hot" loop) are not neccly a representative measure of qemu 
performance.

Paul




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