[TUHS] PDP-11 legacy, C, and modern architectures

Perry E. Metzger perry at piermont.com
Sat Jun 30 05:02:16 AEST 2018

On Fri, 29 Jun 2018 10:51:26 -0700 Larry McVoy <lm at mcvoy.com> wrote:
> > But I think my usage tells you something important: that the
> > performance of individual cores will, inevitably, become
> > increasingly tiny compared to the performance of the system they
> > are in ....  
> Yeah, so what?  That wasn't the point being discussed though you
> and Perry keep pushing it.  

Perhaps we're not agreed on what was originally motivating the
discussion. I believe we started with whether modern parallel
computing environments might need something more than C. I think the
original hardware question this spawned was: is dealing with lots of
cores simultaneously here to stay, and do you get something out of
having language support to help with it? We were trying to address
that question, and given that, I think we've been on point.

Single programs that have to handle large numbers of threads and
cores are now common. Every interesting use of the GPU on your
machine is like this, including the classic ones like rendering
images to your screen, but also newer ones like being exploited
for all sorts of purposes by your browser that aren't related to
video as such. Your desktop browser is a fine example of other sorts
of parallelism, too: it uses loads of parallelism (not merely
concurrency) on a modern desktop to deal with rapid processing
of the modern hideous and bloated browsing stack.

As for whether there's an advantage to modern languages here, the
answer there is also "yes", Mozilla only really managed to get a
bunch of parallelism into Firefox because they used a language (Rust)
with a pretty advanced linear type system to assure that they didn't
have concurrency problems.

Perry E. Metzger		perry at piermont.com

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