On Wed, Aug 19, 2020 at 03:04:56PM -0700, Linus Torvalds wrote: > On Wed, Aug 19, 2020 at 12:41 PM <pet...@infradead.org> wrote: > > > > I'm not sure I get the "expensive irq_work queues" argument, I fully > > agree with you that adding the atomic op is fairly crap. > > There's an atomic op on the actual runing side too, because of the > whole IRQ_WORK_PENDING thing. > > So you get that double hit. > > Maybe it doesn't matter. I just remember us being very careful to > avoid any unnecessary atomics in the smp_call_function area, but > admittedly I haven't worked on that code for a few years, so ..
Patch #3 trades that atomic for a full barrier. Not a massive win on x86, but still.
