Actually Gofer also compiles to C.
That automatic translation had a cost a factor 200 in speed though.
There was some claim of factor 50 (but that was based upon a
very inefficient C compiler where it worked for, namely turbo c),
supported on paper. But that was old paper. I benched it at factor 200.
Even if you work hard and get it down to factor 50, still that's a factor 50
loss
for nothing.
Cilk for example is just a few functions you can use from *inside* C code.
How is sequoia going to beat Cilk?
Just using a 'library' from within C/C++ is always better than ANL that
indirectly compiles,
thereby losing big efficiency.
Vincent
----- Original Message -----
From: "Andrew Shewmaker" <[EMAIL PROTECTED]>
To: "Vincent Diepeveen" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>; <beowulf@beowulf.org>
Sent: Monday, October 02, 2006 4:03 PM
Subject: Re: [Beowulf] Has anyone actually seen/used a cell system?
On 10/2/06, Vincent Diepeveen <[EMAIL PROTECTED]> wrote:
Not wanting to sound too negative, but total nonsense concept.
First of all this 'sequoia' claims to be a new programming language.
Meaning it'll take a year or 30 until some good compilers for it are
there,
provided someone is going to support it.
Which isn't going to happen.
Like many new programming systems, it compiles to C.
The parallellization basically is based upon complex assumptions for
programmers. So for programmers they don't actually make it easier than
trivial parallellization is via C/C++ function calls.
The sequoia parallellization basically is simplistically over for loops
that
a programmer himself can trivially parallellize too.
Sequoia allows the same source to compile and run on systems with
very different memory hierarchies. It uses MPI on clusters and DMA
on the Cell. It also manages overlays on the Cell. Do you consider a
portable runtime system that manages overlays and streams data
asynchronously trivial to implement?
Further the optimization of sequoia simply doesn't happen. They assume
"kernel libraries" solve the problem. Interestingly it mentions
explicitly:
"if kernel libraries could be obtained, such as FFTW and the intel MKL
for
PCs, or the IBM SPE matrix library for Cell, we call these libraries from
Sequoia leaf tasks".
In short if some algorithm has not been implemented for sequoia, sequoia
is
unusable. Others may do the work as usual to promote sequoia.
As I understand it, the leaf tasks can be written in C, Fortran, or
whatever.
Saying Sequoia is unusable is like saying that MPI is unusable.
--
Andrew Shewmaker
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