|You know I love to write about performance comparisons, right?|
I just came across the one I saw some time ago and forgot about it, but now it's linked from the Wikipedia article about OpenVZ. The paper (presented at OLS'08) is comparing performance of OpenVZ, Linux-VServer, Xen, KVM and QEMU with the performance of non-virtualized Linux. The results are shocking! OpenVZ is twice slower than reference system when doing bzip -9 of an iso image! Yet better, on a dbench test OpenVZ performance was about 13% of a reference system (which is almost eight times slower), while Linux-VServer gave about 98%.
Well guys, I want to tell you just one thing. If someone offers to sell you a car for 13% of the usual price — don't buy it, it's a scam and a seller is not to be trusted. If someone tells you OpenVZ is 2 (or 8) times slower than non-virtualized system — don't buy it either!
I mean, I do know how complicated it is to have a sane test results. I spent about a year leading SWsoft QA team, mostly testing Linux kernels, and trying to make sure test results are sane and reproducible (not dependent on the moon phase etc). There are lots and lots of factors involved. But the main idea is simple: if results doesn't look plausible, if you can't explain them, dig deeper and find out why. Once you will, you will know how to exclude all the bad factors and conduct a proper test.
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