Re: [Discuss-gnuradio] Upgrade (downgrade?) to a Q6600 CPU

[Marcus D. Leech]

Bob McGwier wrote:
> Are you taking full advantage of the multi threading now available?  Are you
> running a 64 bit version of Linux?
>   
Is it not true that the latest SVN trunk will automatically turn on
SMP/Multi-threaded support?  From what I'm seeing
  from CPU usage, it certainly looks like it's scheduling threads across
multiple CPUs.  One CPU seems to always
  be busier than the others, which is likely where the bottleneck is. 
I'm running an x86_64 system (F10).
> Have you tried compiling GnuRadio with the following flags?
>
> -O3 -msse -msse3 -mfpmath=sse
>
>   
Did that (via CFLAGS="-O3 -msse -msse3 -mfpmath=sse").  That made a
slight improvement.  I also added
  -with-md-arch=x86_64 when I did the "configure".
>
> The gain from the multiple cores is that more threads get "two thirds of
> processor" making the aggregate faster but NOT necessarily the single
> threads.
>
> Bob
>
>   
Indeed, if the single thread that reads data from the USB can't quite
keep up, then the rest of the threads
  won't have any work to do.  I'm wonder if larger buffer sizes in that
chain could possibly help, but that's
  clutching at straws.

-- 
Marcus Leech
Principal Investigator, Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org