On Thu, Oct 13, 2005 at 11:10:26AM -0700, Brooks Davis wrote: > > I don't think you can measure one single interger (or 64bit) increase in face > > of a operation that has to access backing store. Even if there is a > > performance hit, you don't have to build your kernel with the option enabled. > > The one thing I'd be worried about here is that 64bit updates are > expensive on 32bit machines if you want them to be atomic. Relative to > backing store they probably still don't matter, but the might be > noticable. I'd be grateful if you could clarify that point for me. Are you saying that if I write long long foo; ... foo++; then the C compiler generates code for 'foo++' which is not thread-safe? (And therefore I would have to protect it with a mutex or critical section) Or are you saying that the C compiler inserts its own code around foo++ to turn it into a critical section, and therefore runs less efficiently than you'd expect? Regards, Brian.Received on Fri Oct 14 2005 - 07:10:12 UTC
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