On Nov 30, 2021, at 14:47, Christopher Nielsen wrote: > Back in May, @ryandesign mentioned that we have the option of upgrading our > buildbot farm with more powerful CPUs. Said farm is currently hosted on > Xserves, and since the CPUs are socketed, it’s reasonably straightforward.
The new CPU generation is available in hex-core versions which would be a 50% improvement over the quad-core CPUs we have now. And the new CPU generation is made using a newer process with smaller traces, which will result in faster performance at the same speed rating. It's not entirely as straightforward as just replacing the CPUs though, because the newer CPU generation is not compatible with Xserve firmware. It would require replacing the Xserve firmware with Mac Pro firmware, which is possible at the expense of some Xserve functionality, which is an acceptable tradeoff. There's also the matter that the Xserve requires lidless CPUs which reduces the number of places from which one can purchase a CPU since not everybody sells lidless versions, or requires one to purchase a standard CPU and delid the CPU oneself or send it to someone else to have them do it for a fee. I also still haven't made a decision with regard to which CPU speed to seek out. The Xserve shipped in three CPU speed variants but Intel offers something like a dozen different CPU speeds. The choice is constrained by the power consumption of each different speed CPU and the thermal limits of the Xserve. Some of our builds spend more time on disk tasks than CPU tasks. We could increase the speed with which we can produce builds by optimizing mpbb to avoid unnecessary disk work, including unnecessary activations and deactivations of dependencies. See https://trac.macports.org/ticket/62621 for some thoughts on that.
