[concurrency-interest] Synchronization of data read by multiple threads

Chris Purcell chris.purcell.39 at gmail.com
Wed Oct 26 11:43:29 EDT 2005


> You should find it comforting that on nearly all processors, a 
> volatile read costs no more than any other kind of read

I was under the impression that more recent Intels added a read-read 
barrier to the instruction set for this purpose: only older chips don't 
reorder reads.

On the other hand, x86 guarantees write ordering, making write-write 
barriers (and hence volatile writes) cheap-as-free.

Am I missing something?

Cheers,
Chris



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