On 2018/12/12 1:18, Dave Hansen wrote: > 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? >
Do we have a real requirement to do this in practical environment? AFAIK, 1s or even 5s is good enough in some customers environment. Thanks, -Aubrey
