On Thu, Aug 18, 2016 at 08:51:31AM -0700, Andi Kleen wrote:
> > I'd prefer to make updates atomic in multi-threaded applications.
> > The best proxy we have for that is -pthread.
> >
> > Is it slower, most definitely, but odds are we're giving folks
> > garbage data otherwise, which in many ways is even worse.
>
> It will likely be catastrophically slower in some cases.
>
> Catastrophically as in too slow to be usable.
>
> An atomic instruction is a lot more expensive than a single increment. Also
> they sometimes are really slow depending on the state of the machine.
Can't we just have thread-local copies of all the counters (perhaps using
__thread pointer as base) and just atomically merge at thread termination?
Jakub
