From: Nicholas Piggin <npiggin@xxxxxxxxx> Date: Tue, 4 Apr 2017 13:02:33 +1000 > On Mon, 3 Apr 2017 17:43:05 -0700 > Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > >> But that depends on architectures having some pattern that we *can* >> abstract. Would some "begin/in-loop/end" pattern like the above be >> sufficient? > > Yes. begin/in/end would be sufficient for powerpc SMT priority, and > for x86, and it looks like sparc64 too. So we could do that if you > prefer. Sparc64 has two cases, on older chips we can induce a cpu thread yield with a special sequence of instructions, and on newer chips we have a bonafide pause instruction. So cpu_relax() all by itself pretty much works for us.
