Subj : Re: Adding thread support for C...
To   : comp.programming.threads
From : Chris Friesen
Date : Tue Aug 02 2005 05:52 pm

Marcin 'Qrczak' Kowalczyk wrote:
> Charles Bryant <n519629998.ch@chch.demon.co.uk> writes:
> 
> 
>>However, it would be wrong to assume that, for example, an atomic
>>increment operation must be faster than a lock/increment/unlock
>>sequence, when it might be slower.
> 
> 
> Well, on a sensible implementation it will not be slower because it
> can be implemented by this.

Really?  How would you make the lock/modify/unlock cycle faster than a 
single atomic increment?

In the optimal uncontended case each of the lock/unlock will be an 
atomic operation, so you end up with one extra atomic as well as 
whatever modification that you were trying to do.



Chris

.