Nelson,
Nelson B Bolyard wrote:
Julien R Pierre - Sun Microsystems wrote, On 2009-01-21 15:03:
You are running Darwin, and freebl does not have any optimizations for
RSA on darwin. It has some assembly optimizations on most other x86
platforms. But on Darwin, freebl is built with plain C code, and no
assembly at all. That is one reason why the code is running a lot slower.
Even if you end up building NSS with optimizations, they use the regular
multiply instructions, which performs best on AMD chips, but not as well
on Intel CPUs. For Intel, one needs to use the SSE2 and above
instructions set, which NSS currently doesn't do - except on one
platform, Linux.
Is there any reason why we can't use the same optimizations on Darwin/x86
as we use on Linux?
I don't know all that much about how we should handle things
specifically on Darwin regarding optimizations. We should at least be
able to incorporate you original multiply x86 optimizations (the
non-SSE2 assembly code).
For the SSE2 code, there are remaining questions for Darwin, such as
whether binaries are marked for specific instruction sets, as they are
in Solaris, but not in Linux.
There is also the question of whether Darwin even needs non-SSE2
binaries at all - if we are talking strictly about MacOSX, I think the
first chips it supported were Intel Core Duo with SSE2 . But if we are
talking about open-source Darwin, it might or might not support older
chips that don't have SSE2, such as some 32-bit Athlon XP and MP, or
older Intel chips (all pre-Pentium 4 chips).
I don't like much the way that we implemented SSE2 on Linux - together
in a single freebl shared library with the non-SSE2 version. That stands
in the way of us implementing SSE2 in Solaris. See bug 458480 about
that. Also bug 439199 about the Windows implementation.
I am not sure what's the best answer for Darwin. But from an
architectural point of view, I would prefer that we implement SSE2
differently than we did on Linux, and put it in a separate freebl on all
platforms, rather than together with a separate non-SSE2 implementation
in the same freebl library. If Darwin doesn't need non-SSE2 binaries,
then we could only have a single SSE2-enabled freebl shared lib for that
platform .
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