Which OS is Fastest -- FreeBSD Follow-Up

Jeffrey Rothman and John Buckman

In the weeks after our article "Which OS is Fastest for High-Performance Network Applications?" was published in Sys Admin (July 2001), we received many emails from readers in the FreeBSD community who were unhappy with the benchmark results.

They stated that the FreeBSD operating system, when installed "out of the box" is configured by default to be very safe and reliable, and that the FreeBSD community purposely chose reliability over speed in configuring the default operating system. They contend that few production sites run FreeBSD as pre-configured. Rather, most FreeBSD systems administrators tune the operating system by reading "man tune", by joining the FreeBSD discussion groups, and by reading other FreeBSD documentation. These readers felt that our "out of the box" test did not represent how FreeBSD is used in the real world, and thus that our benchmark results were unfair.

Based on the FreeBSD readers’ statement that "most systems administrators tune FreeBSD before putting it in production", we agreed to apply their tuning tips, re-run our tests, and publish the results. We started an email discussion list for all interested readers to discuss, agree, and suggest performance improvement changes to our FreeBSD system configuration. We applied their 17 OS changes and recompiled the kernel. Our revised test results are shown in Figures 1-3.

File System Test -- After FreeBSD Tuning

In our originally published file system test, FreeBSD did poorly, because by default the system uses synchronous updates of file system metadata. This makes FreeBSD more reliable in the event of an unexpected system shutdown (a crash or power outage), but negatively impacts speed.