Messages in this thread | | | Date | Sun, 26 Apr 1998 15:56:31 -0700 | From | "David S. Miller" <> | Subject | Re: faster strcpy() |
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Date: Sun, 26 Apr 1998 14:48:02 -0700 (PDT) From: Dean Gaudet <dgaudet-list-linux-kernel@arctic.org>
Which of course can't be used at all on SMP boxes; and I even have doubts about its performance on a UP box when you've got more than one task going. strcpy() is not an uncommon routine, if all the processes on a box were using the FPU to do strcpy() it probably won't be a pretty thing -- every context switch would require FPU switching as well.
For some things on some architectures, the performance gain from FPU based memcpy/csum_copy/etc. are so large that we even do it in the kernel on sparc64.
The trick is to have a heuristic which decides whether the cost of (possible) extra FPU saves/restores overcomes the gain in performance from the FPU version of the code. This heuristic is available always for the memcpy/csum_copy cases, but it isn't (and would almost never be met in any event) for the str{n}cpy() cases.
Later, David S. Miller davem@dm.cobaltmicro.com
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