On 12/10/18 4:24 PM, Aubrey Li wrote: > The tracking turns on the usage flag at the next context switch of > the task, but requires 3 consecutive context switches with no usage > to clear it. This decay is required because well-written AVX-512 > applications are expected to clear this state when not actively using > AVX-512 registers.
One concern about this: Given a HZ=1000 system, this means that the flag needs to get scanned every ~3ms. That's a pretty good amount of scanning on a system with hundreds or thousands of tasks running around. How many tasks does this scale to until you're eating up an entire CPU or two just scanning /proc?
