6 ms·
If you have switched PCIe anyways I would have loved a Mac Pro with a "passive" switched PCIe backplane where you can hotplug PCIe devices in including M2 CPU P
by sprash 3y ago
If you have switched PCIe anyways I would have loved a Mac Pro with a "passive" switched PCIe backplane where you can hotplug PCIe devices in including M2 CPU PCIe cards. Also polish the OS accordingly that you can upgrade/switch your CPU in live operations without shutting down the OS or may be even run Apple silicon CPUs and x86 CPUs alongside.
- dijit 3y agoI think we collectively decided that we didn't want hot-swap CPUs and instead wanted inexpensive compute (so we could have a lot more of it) when we let SPARC die.
- hosteur 3y agoWhy must hot swap cpu inherently be expensive?
- dijit 3y agoBecause engineering effort is not free.
- hosteur 3y ago> Because engineering effort is not free. Obviously, but that does not explain why CPU hot swap is inherently expensive. Engineering effort is required to make any CPU. Why must the engineering effort specifically relating to CPU hot swap inherently cause architectures that supports CPU hot swap significantly expensive compared to architectures that does not? As a lay man without any experience with actual semi conductors outside of university, I would have thought that this would mostly be something that needs to be designed and specified once and then it could be mass produced. Clearly it will take some effort and you would have to spend some gates on it in the chip design. Considering all the other stuff that are in modern CPUs and chipsets, I would have thought it would be possible to do rather cheaply if mass produced.
- wongarsu 3y agoI believe IBM Z Systems still have hot-swappable CPUs. Of course that one is also niche for the same reason: we prefer lots of cheap commodity servers instead of few super reliable rack-sized computers
- meindnoch 3y agoWhat is exactly the use case for hot-swapping CPUs?
- wsc981 3y agoUptime [0] ——— [0]: http://bash.org/?search=Uptime&sort=0&show=25 http://bash.org/?search=Uptime&sort=0&show=25
- trollied 3y agoSwapping a failed device for a working one, without powering down the machine.
- ohgodplsno 3y agoCurious to see how you imagine swapping all the registers and caches of a currently broken CPU (so, unable to do anything including sending those registers somewhere). Because if you don't, sure, you didn't technically power down your machine, you just fucked up your entire stack, stack pointer goes to the wrong place, checks based on hardware are now wrong... In effect, you powered down the machine because your OS will just stop working, your running processes are fucked, etc.
- sprash 3y agoThe equivalent to flushing your register state is more comparable to a context switch than a complete shut down. Also Thanks to PCIe CPU swapping could be done in pure software at the OS level. No further hardware changes required. Simply copy the contents of your RAM to the other CPU card and manage the hand-off. This is clearly different from a complete shutdown e.g. all devices on the PCIe bus would be able to keep their state. A good programmer familiar with the target OS and inner workings of PCIe could deliver a working prototype within a week, production ready within less than a year.
- solardev 3y agoAs a web developer unfamiliar with the hardware stack, I was surprised by this part... > A good programmer familiar with the target OS and inner workings of PCIe could deliver a working prototype within a week, production ready within less than a year. Could you please explain why it'd be normal to take a year to go from prototype to production in this case? What would happen in that one year, starting from a working prototype?