Erlang & Hyperthreading

Ernie Makris <>
Mon Feb 27 15:05:31 CET 2006

If you want to try out the new smp version snapshot of R11B, surf to:

Valentin Micic wrote:
> We've been briefly evaluating SUN Niagara -- single 8-core CPU.
> Initiall results were great -- we were not able to make this machine
> busy; however, it seems that we did experience some problems with
> TCP/IP. Well not sure why, it could be because we never build Erlang
> on Solaris 10, rather, we've just moved it accross... we are going to
> carry on with this evaluation at the later stage.
> We're still using R9, which doesn't seem to be compiling on Solaris 10
> -- I haven't tried it myself, but been told that some headers are
> missing from Solaris 10. It seems that the best thing to do would be
> to move everything to R10, but there aren't enough hours in a day.
> Valentin.
> PS
> As far as Linux is concerned, depending on distribution, we had
> different experiences/frustrations. What is defeating about Linux is
> that one has to be a product manager in order to figure out what
> patches to install where and when, as far as RedHat is concerned.
> OTOH, we got much better results once we've moved to version 4,
> including much better CPU scheduling. In addition, we had lots of
> issues with various storage arrays (EMC, HP Eva & HP XP12000) -- once
> system gets busy in terms of disk I/O, we saw a lots of D's  (D being
> an unconditional process suspension due to resource unavailability).
> Once we increased number of threads, as per Ulf's comment to some
> posting on the list, our performance increased dramatically. We still
> saw D's, but because drivers were serviced by different threads, we
> did not see main thread blocking. Come think of it, I've never thanked
> Ulf... Hey, Ulf -- thanks a lot.
> ----- Original Message ----- From: "Richard A. O'Keefe"
> <>
> To: <>
> Sent: Monday, February 27, 2006 5:31 AM
> Subject: Re: Erlang & Hyperthreading
>> "Ryan Rawson" <> wrote:
>> You could expect up to 8 CPUs on commodity Intel hardware as well.
>> Generally hyperthreaded CPUs show up as multiple CPUs on Linux -
>> but be warned, I heard of performance improvements by turning off HT.
>> Well, this is Solaris 10, not Linux, and it's UltraSPARC (presumably
>> Ultra III), not Intel.  Perhaps someone else may have more accurate
>> information; I think it's effectively 8 x (4-way hyperthreaded) CPUs,
>> not 1 x (8-way hyperthreaded).   In any case, different horse from
>> different
>> stable, so maybe the results will be different.  Maybe _this_ horse will
>> learn to sing? 

More information about the erlang-questions mailing list