Re: basic_string::release and thread safety: what about

[Richard Henderson <rth at cygnus dot com>]

On Tue, Jul 06, 1999 at 07:13:55PM -0700, Richard Henderson wrote:
> No it isn't.  On all extant SMP systems, cache coherency is free.

Let me amend that with 

  Free in the sense that you get it whether you ask for it or not. 

You do still pay for cache ping-pong.  But it's something the
system controler does, over which userland (or indeed even the
kernel) has no control. 

Note that inter-cpu cache coherency is different than the issues
that surround coherency wrt some DMA controlers on UP systems.


r~