Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures

On Sat, Aug 18, 2007 at 03:41:13PM -0700, Linus Torvalds wrote:

On Sat, 18 Aug 2007, Paul E. McKenney wrote:

quoted

One of the gcc guys claimed that he thought that the two-instruction
sequence would be faster on some x86 machines.  I pointed out that
there might be a concern about code size.  I chose not to point out
that people might also care about the other x86 machines.  ;-)

Some (very few) x86 uarchs do tend to prefer "load-store" like code 
generation, and doing a "mov [mem],reg + op reg" instead of "op [mem]" can 
actually be faster on some of them. Not any that are relevant today, 
though.

;-)

Also, that has nothing to do with volatile, and should be controlled by 
optimization flags (like -mtune). In fact, I thought there was a separate 
flag to do that (ie something like "-mload-store"), but I can't find it, 
so maybe that's just my fevered brain..

Good point, will suggest this if the need arises.

							Thanx, Paul