On Fri, Aug 31, 2018 at 08:58:39AM -0700, Dave Hansen wrote: > On 08/31/2018 08:48 AM, Yu-cheng Yu wrote: > > To trigger a race in ptep_set_wrprotect(), we need to fork from one of > > three pthread siblings. > > > > Or do we measure only how much this affects fork? > > If there is no racing, the effect should be minimal. > > We don't need a race. > > I think the cmpxchg will be slower, even without a race, than the code > that was there before. The cmpxchg is a simple, straightforward > solution, but we're putting it in place of a plain memory write, which > is suboptimal. Note quite, the clear_bit() is LOCK prefixed.
