[jmm-dev] Sequential Consistency
Stephan.Diestelhorst at arm.com
Thu Apr 3 12:17:02 UTC 2014
On Monday 24 February 2014 22:54:21 Paul E. McKenney wrote:
> On Sun, Feb 23, 2014 at 01:06:42PM +0400, Aleksey Shipilev wrote:
> > On 02/22/2014 07:59 PM, Doug Lea wrote:
> > Being the language guy, I think the hardware not being able to provide
> > the sane SC primitives should pay up the costs. The hardware which makes
> > it relatively easy to implement the non-tricky language memory model
> > should be in the sweet spot.
> All hardware I know of has a non-trivial penalty for its SC primitives,
> so there is a place for non-SC algorithms.
I am not quite sure, how HW can pay a cost. Ultimately, it is program
performance or correctness that suffers from too much / too little
SC-ification. (And yes, there is a myriad of reasons for correctness
issues, even with SC.) So in my mind, the question is how do we (1)
make it easy for the programmer to specify the right intent of when SC
(etc.) is needed (or how can we automate the process) and then (2) which
patterns will emerge from that that we (the HW dudes) need to
efficiently support without going SC everywhere.
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