Good diagnosis, wrong conclusion [LWN.net]

Good diagnosis, wrong conclusion

Posted Oct 3, 2007 7:11 UTC (Wed) by njs (guest, #40338)
In reply to: Good diagnosis, wrong conclusion by ncm
Parent article: Memory part 2: CPU caches

>More to the point, when 32-core PPCs are several times faster than 32-core x86es, you will naturally become more interested in how to program them reliably.

But by that point, we won't be using languages with shared-everything concurrency models.

...Please?

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Of course we will

Posted Oct 3, 2007 20:24 UTC (Wed) by khim (subscriber, #9252) [Link]

Big programs are developed in 10-15 years, so we can be pretty sure programs developed today and even yesterday will be used on 32-CPU cores. Sure, some parts can (and will) be replaced, but a lot of code and binaries will be reused. A lot of distributions still include GTK+ 1.2.x because not all applications are rewritten yet - and GTK+ 2.0 is over five years old. And it's just upgrade (not even replacement) of one library (not change of language).

We will have 32-core CPUs in five years - do you really believe that someone will abandon billions lines of existing code by then ?

Of course we will

Posted Oct 4, 2007 21:54 UTC (Thu) by jzbiciak (✭ supporter ✭, #5246) [Link]

Right, but will new, highly parallel programs be developed in the same languages? I think it's acceptable to say that old programs don't benefit as much from new features.

The requirement to be compatible does not necessarily include the requirement to provide peak performance.

Of course we will

Posted Oct 5, 2007 17:45 UTC (Fri) by hazelsct (guest, #3659) [Link]

You forgot about libraries. It's easy to rip-and-replace a ray tracing engine, (non)linear system solver, etc. for one written in Fortress with a similar interface, and still keep the same expensive C++, Java, or Python high-level framework.

As for your example, what still uses GTK+ 1.2, aside from XMMS 1 (XMMS 2 doesn't) and groach? If this were a real performance or other problem, we would have a 1.2-compatible wrapper over 2.0.