[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]
Re: mutexes, locks and so on...
On Fri, Nov 12, 2010 at 02:30:58PM +0100, Johnny Billquist wrote:
> Hmm. The thing with rwlocks though is that the actual concept is
> just that you have locks that you want to grab, with the expanded
> idea that you can have them at two different levels. read or write.
> There is nothing inherently CAS about that. On a VAX, I can easily
> implement this with native instructions, but it will not be anything
> near a CAS. But now, they are more or less forced to go via a CAS
> anyway, for what I'd consider no good reason.
- The cheapest way to implement rwlocks on modern computers is with CAS.
- rwlocks work badly in the real world. In applications where they do make
sense other primitives offer a better deal. For example Linux seqlocks
or distributed locks with a per-CPU component. Therefore it doesn't
make sense to spend time enhancing rwlocks.
Main Index |
Thread Index |