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New Bonnie++ Releases

Today I released new versions of my Bonnie++ [1] benchmark. The main new feature (in both the stable 1.03b version and the experimental 1.93d version) is the ability of zcav to write to devices. The feature in question was originally written at the request of some people who had strange performance results when testing SATA disks [2].

Now I plan to focus entirely on the 1.9x branch. I have uploaded 1.03b to Debian/unstable but shortly I plan to upgrade a 1.9x version and to have Lenny include Bonnie++ 2.0x.

One thing to note is that Bonnie++ in the 1.9x branch is multi-threaded which does mean that lower performance will be achieved with some combinations of OS and libc. I think that this is valid as many applications that you will care about (EG MySQL and probably all other modern database servers) will only support a threaded mode of operation (at least for the default configuration) and many other applications (EG Apache) will have a threaded option which can give performance benefits.

In any case the purpose of a benchmark is not to give a high number that you can boast about, but to identify areas of performance that need improvement. So doing things that your OS might not be best optimised for is a feature!

While on this topic, I will never add support for undocumented APIs to the main Bonnie++ and ZCAV programs. The 1.9x branch of Bonnie++ includes a program named getc_putc which is specifically written to test various ways of writing a byte at a time, among other things it uses getc_unlocked() and putc_unlocked() – both of which were undocumented at the time I started using them. Bonnie++ will continue using the locking versions of those functions, last time I tested it meant that the per-char IO tests in Bonnie++ on Linux gave significantly less performance than on Solaris (to the degree that it obviously wasn’t hardware). I think this is fine, everyone knows that IO one character at a time is not optimal anyway so whether your program sucks a little or a lot because of doing such things probably makes little difference.

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