[boost] Re: [shared_ptr] PPC implementations updated

From: Miro Jurisic (macdev_at_[hidden])
Date: 2005-04-08 16:07:06

In article <4256E629.5C47C47C_at_[hidden]>, Alexander Terekhov <terekhov_at_[hidden]> 
wrote:

> Peter Dimov wrote:
> 
> > It might be good enough anyway... it's only two more instructions, 
> > after all. stwcx. is uncontended on zero. 
> 
> It is contended on strong count and uncontended on weak count. On MP, 
> lock()ers will simply play Ping-Pong with zero fighting each other. 
> Even if you change the code and do that silly "cleanup write" out of 
> the loop, it will still increase traffic, I'm afraid. So, again, get 
> rid of it unless the issue is provably real (not a myth created from 
> miscommunication or whatever).

I think that given the choice of better performance and better safety we should 
err on the side of safety until the faster version is provable safe, not the 
other way around (as you seem to be suggesting).

meeroh