Why We Run FreeBSD current at Netflix (Drew Gallatin)
Overview
Drew Gallatin explains why Netflix chose to run their CDN appliance on the FreeBSD-current branch, instead of a FreeBSD-stable release.
-
Easier to upstream changes because you are running the same version of the OS as upstream. When you are running an older version, often APIs and function signatures will be different between your version and the
mainversion, which essentially requires that you -
Amortizes and lowers the cost of upgrades. when BSD makes a breaking change, you find it right away instead of years later, which makes it much easier to zero in on the break.
-
Gives the example of an upstream regression that caused a 20% increase in CPU utilization. Running git bisect over the past 3 weeks of changes, they were able to determine that the cause was a change to the sort algorithm used during boot to sort SYSINITs from bubble sort to merge sort. SYSINITs are sorted by a priority field. SYSINITs with the same priority should be able to be run in any order. It turned out that the driver subsystem sometimes needs to pick between different compatible drivers, and will pick the first such driver offered during init. The change to merge sort changed the order that SYSINITs with equal priority from what they had been under the previous sort algorithm, and that caused the kernel to pick an older, worse CPU frequency driver.
Since we found the bug within a week or so of it hitting the tree, the developer responsible was incredibly responsive. All th details were fresh in his memory. Contrast this to somebody reporting a bug in something you did 3-4 years ago.