A tale of an impossible bug: big.LITTLE and caching
> Worse, not even the ARM ISA is ready for this. An astute reader might realize that computing the cache line on every invocation is not enough for user space code: It can happen that a process gets scheduled on a different CPU while executing the __clear_cache function with a certain cache line size, where it might not be valid anymore.I rather see the problem in the fact that there seems to be no possibility to say to the Linux scheduler: Only schedule this process/thread between cores that have the same cache line size. Or add an attribute when some thread is created on the cache line size of the cores it is allowed to run. Or an attribute when some thread is created for "allow arbitrary cache line size but don't let it run on cores with a different size". This way it would suffice to check for the cache size on program or thread start.