Yeah, although maybe the flag should decay after a while? You want to avoid either spending significant percentages of your time trying to run processes that make no progress because they need unavailable instructions or delaying processes significantly because they are waiting for resources they no longer need.

This sounds a little bit subtle, in the way most operating system policy problems are subtle, but far from intractable. Most of the time all your processes are making progress and either all your cores are busy or you don't have enough runnable processes to keep them busy. In the occasional case where this is not true, you can try optimistically deflagging processes that have made some progress since they were last flagged. Worst case, you context switch an idle core to a process that immediately faults. If your load average is 256 you could maybe do this 256 times in a row at most, at a cost of around a microsecond each? Maybe you have wasted a millisecond on a core that would have been idle?

And you probably want the flag lifetime to be on the order of a second normally, so you're not forced to make suboptimal scheduling decisions by outdated flags in order to avoid that microsecond of wasted context switching.