Re: maximum theoretical speedup with dual quad processors
Re: maximum theoretical speedup with dual quad processors
- Subject: Re: maximum theoretical speedup with dual quad processors
- From: Michael Vannorsdel <email@hidden>
- Date: Sat, 31 Jan 2009 23:56:22 -0700
If your original algorithm is scalar, you can get upto 4x increase by
moving to SIMD (SSE2/3) if your algorithms can be paralleled. Add
that to the 7 extra cores and you can get upto 32x speed up. In the
real world you're very (very) unlikely to reach max throughput because
of data dependencies, memory bandwidth limits, cache capacity limits,
and thread preemption to name a few.
And you can manage threads with pthread functions (pthread_create) or
NSThread class (+[detachNewThreadSelector:toTarget:withObject:]).
On Jan 31, 2009, at 3:04 PM, email@hidden wrote:
I have a bullet-proof scientific app I developed using cocoa. I just
purchased a new MacPro with the dual quad processors.
Earlier posts attempting to determine MAXIMUM theoretical speedup have
gotten bogged down with semantic differencea between a corea and a
CPUa.
Having done EXTENSIVE multi-processing on UNIX machines using MPI, I
was
hoping I could achieve a speedup on my application exceeding 2 times
and
hopefully approachig numcores - 1 times (7 in this case).
There IS a know bug with the NSInvocationQueue method on intels using
10.5.6 which I have read will be fixed on 10.6.
my question are:
(1) Is the ANYONE out there who has actually done scientific
computing on
the quad-core intel machines?
(2) Have you achieved a speedup beyond number of CPU's (2)?
(3) Has anyone used OpenMP with optional (LLVM or gcc 4.2) compilers?
(4) If so where do I install the xomp foler I downloadd which is
compatible with my machine and OS.
(5) Please don't waste your time explaining the semantic differences
between cores and cpu's, I don't care what you call them, all I need
to
know is MAXIMUM speedup.
Anyone who can point me in the right direction for running concurrent
methods NOT using NSOperationQueue with NSInvocationOperations would
make
me VERY VERY happy.
Thanks again everyone.
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