Subj : Re: A question about atomic_ptr
To   : comp.programming.threads
From : Joe Seigh
Date : Sat Apr 16 2005 09:35 am

On Fri, 15 Apr 2005 21:22:01 -0700, Chris Thomasson <_no_damn_spam_cristom@_no_damn_comcast.net_spam> wrote:

>> Well, we take what we can get.  When you get lemons, you make lemonade.
>> When you get hardware, you make software.
>
> LOL!

I'm tempted to make that my sig.  That ought to go over well on comp.arch,
you think?

>
> <hardware rant>
> Isn't assembly language great! Its basically created by experienced hard
> working hardware folk who "seem" to think an efficient implementation of TAS
> should be "enough" for all types of threaded programming. I could picture a
> hardware guy thinking that DWCAS is basically only useful for 32-bit
> programs that want to have 64-bit atomic ops, to be 64-bit ready so to
> speak...
>
> They give the ability for advanced lock-free algorithms on 32-bit and did
> not event seem to realize it. That can "possibly" be a real reason that
> would account for the fact that DWCAS is *not "reliably" ported to 64-bit
> systems.
> </hardware rant>
>
>
>
>
> * It is on Intel extensions, and "some" AMD's; Per-cpu "features", damn...
>
> ;)
>
>
>
>
> <rant2>
> What the heck was that cmp8xchg16 thing all about!
> </rant2>
>

Well, it will eventually be on all Intel and AMD cpus.  The company that's
going to be in trouble will be Sun since they're going to highly multi-threaded
processors, Niagra and Rock, which are Sparc architectures and don't have
DWCAS, and won't be able to exploit DWCAS.  What's strange is Sun Research
has a group (Moire, Herlihy, ...)  working on lock-free algorithms using the
mythical 2CAS (CAS on 2 separate memory locations) and Sun ignores it.  Yet
Sun is flogging the Throughput Computing as the hot new thing.  WTF is Sun
funding research that it deliberately ignores?  Someone need to take a
cluebat to Sun's corporate executives.  Sun is not a commodity company
and they're going to get creamed.  It doesn't matter how many cores they
put on their multi-core ships since they're not going to be able to uniquely
exploit them.  Commodity cpu's will be cheaper.


-- 
Joe Seigh

.