Messages in this thread | | | From | Yury Norov <> | Date | Fri, 29 Jan 2021 12:51:32 -0800 | Subject | Re: [PATCH 0/6] lib/find_bit: fast path for small bitmaps |
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On Fri, Jan 29, 2021 at 12:45 PM Yury Norov <yury.norov@gmail.com> wrote: > > Bitmap operations are much simpler and faster in case of small bitmaps, whicn > fit into a single word. In linux/bitmap.h we have a machinery that allows > compiler to replace actual function call with a few instructions if bitmaps > passed into the function is small and its size is known at compile time. > > find_*_bit() API lacks this functionality; despite users will benefit from it > a lot. One important example is cpumask subsystem, when NR_CPUS <= BITS_PER_LONG. > In the very best case, the compiler may replace a find_*_bit() call for such a > bitmap with a single ffs or ffz instruction. > > Tools is synchronized with new implementation where needed.
Sorry for the broken enumeration . If it's too confusing, please let me know and I'll resend.
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