[Cbe-oss-dev] GCC inline memcpy() from local store causes bad page fault
pinskia at gmail.com
Thu Mar 22 08:16:00 EST 2007
On 3/21/07, Segher Boessenkool <segher at kernel.crashing.org> wrote:
> Are ucoded insns really _that_ bad on CBE? You certainly
> should keep lha/lwa with -Os btw.
Yes as they cause the other hyperthread to stall while the waiting for
the microcoded instruction to finish and there is a 7cycle bubble for
the decoding stage. So yes they are really that bad on the current
Cells. I am trying to remember but I think the speed up is around
10-20%, maybe higher for multiple threaded programs.
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