Messages in this thread | | | Subject | Re: Alternative implementation of the generic __ffs | From | Joe Perches <> | Date | Sat, 19 Apr 2008 20:06:57 -0700 |
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On Sun, 2008-04-20 at 01:29 +0300, Matti Aarnio wrote: > I am curious, why not take the code already in glibc ffs() for ARM ? > That is, if the ffs() is all that important detail in kernel ?
Here's test results with the glibc ffs implementation. (small const is still using slower add rather than or)
$ gcc -Os -fomit-frame-pointer ffs.c $ ./a.out Original: 3155 tics, 8331 tics New: 4211 tics, 8793 tics Smallest: 4019 tics, 7754 tics Small const: 3552 tics, 6308 tics glibc: 2816 tics, 6911 tics Empty loop: 1516 tics, 2244 tics
$ gcc -O2 -fomit-frame-pointer ffs.c $ ./a.out Original: 3155 tics, 7828 tics New: 4792 tics, 8825 tics Smallest: 4401 tics, 7155 tics Small const: 3539 tics, 5805 tics glibc: 2720 tics, 7061 tics Empty loop: 1516 tics, 2148 tics
$ gcc -O3 -fomit-frame-pointer ffs.c $ ./a.out Original: 3080 tics, 7706 tics New: 4721 tics, 8663 tics Smallest: 4334 tics, 7116 tics Small const: 3466 tics, 5672 tics glibc: 2649 tics, 6939 tics Empty loop: 1444 tics, 2012 tics
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