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QEMU: Gentoo Guest Performance

It took me 12 days (not months as I previously guessed) but I have an instance of Gentoo installed as a QEMU guest. That includes the time of the initial installation of Gentoo, which went very smoothly due to their superb documentation, the emergence of links the terminal mode web browser, which brought in more than 200 dependencies including the entire X Window System, and a failed attempt to emerge Gnome, which would have brought in another 250 packages but errored out when there are 100 to go. (After the failed Gnome installation, I wanted to clean up a bit and retry. One of the cleanup commands I used is emerge --depclean, which wiped out the 150 packages already installed for Gnome.)

And here's the benchmark result:

On the surface, Gentoo's index of 11.9 compares unfavorably against Ubuntu's 56.0. However, on close inspection, I discovered that the Ubuntu guest's clock is running much slower then the host's clock, which inflated Ubuntu's index.

An rough estimate shows that Ubuntu's clock is running at one quarter of the regular clock speed. So the Ubuntu number should be roughly 14.0, still better than the Gentoo number. Incidentally, with the new lower number, the emulated QEMU system falls into the Pentium 200 category.

So for all that long compile time, I get a Gentoo system that runs at 85% the speed of Ubuntu. Apparently for the system emulated by QEMU, none of the optimizations that I hear Gentoo enthusiasts talking about matters.



Re: QEMU: Gentoo Guest Performance

performance comparisons for programs (or operating systems) run inside a virtual machine are meaningless. The clock is not just a factor of X off, it is not even regular. If you make performance comparisons, you must run the software on real hardware.

Re: QEMU: Gentoo Guest Performance

it's not the speed that matters the most on gentoo, but its great flexibility and high quality documentation and the great community behind it. I'll take the test on the same real hardware and report the results.

QENU: The Open Source Virtualizer

I rerun the benchmark program inside a Debian 4.0 i386 guest OS. And the result is captured in this screenshot: [QEMU Full Virtualization Mode Performance]

A comparison with my earlier results shows that the result of 219.0 dhrystone for QEMU in full virtualization mode is 18.4 times the 11.9 dhrystone for QEMU in emulator mode. Note that these benchmarks were run on the same physical hardware.

The benchmark result ran in the host OS is 288.6 dhrystone.


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