On Wed, 18 Jun 2008, Jeremy Fitzhardinge wrote: > > It's not cmpxchg, just xchg. > In other words, is: > > lock btr $_PAGE_BIT_RW, (%rbx) Well, we can actually do it as lock andl $~_PAGE_RW,(%rbx) although we haven't bothered (I've wanted several times to make clear_bit() do that, but have never gotten around to it - mainly because old gcc versions didn't work with __builtin_constant_p() in inline functions - so you have to do the macro from hell) And yes, the "lock andl" should be noticeably faster than the xchgl. Linus _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
