Messages in this thread | | | From | Yury Norov <> | Subject | [PATCH v3 0/5] lib/find: add find_nth_bit() | Date | Sat, 17 Sep 2022 20:07:10 -0700 |
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Kernel lacks for a function that searches for Nth bit in a bitmap. Usually people do it like this: for_each_set_bit(bit, mask, size) if (n-- == 0) return bit;
Which is not so elegant and very slow.
This series adds fast routines for this task, and applies them where appropriate.
v1: https://lore.kernel.org/lkml/20220706182300.70862-4-yury.norov@gmail.com/T/ v2: https://lore.kernel.org/lkml/CAAH8bW_RYG_Tbpip=BkSFAymDm2y3jJBqTi0PJWA=H-a-L_3tg@mail.gmail.com/T/ v3: - add bitmap_weight_and() and use it in cpumask_local_spread(); - rework find_nth_bit() family: similarly to [1], introduce FIND_NTH_BIT(), and optimize the function to return earlier when it's known that the rest of bitmap can't meet the requirement. - patch "lib/nodemask: inline next_node_in() and node_random()" has been merged, so drop it from this series.
On top of: [1] https://lore.kernel.org/lkml/20220915020730.852234-1-yury.norov@gmail.com/T/
Yury Norov (6): lib/bitmap: don't call __bitmap_weight() in kernel code lib/bitmap: add bitmap_weight_and() lib: add find_nth(,and,andnot)_bit() lib/bitmap: add tests for find_nth_bit() lib/bitmap: remove bitmap_ord_to_pos cpumask: add cpumask_nth_{,and,andnot}
fs/ntfs3/bitmap.c | 4 +- include/linux/bitmap.h | 13 +++++- include/linux/bitops.h | 19 +++++++++ include/linux/cpumask.h | 55 +++++++++++++++++++++++++ include/linux/find.h | 86 ++++++++++++++++++++++++++++++++++++++++ include/linux/nodemask.h | 3 +- lib/bitmap.c | 68 ++++++++++++------------------- lib/cpumask.c | 28 ++++++------- lib/find_bit.c | 44 ++++++++++++++++++++ lib/find_bit_benchmark.c | 18 +++++++++ lib/test_bitmap.c | 47 +++++++++++++++++++++- 11 files changed, 320 insertions(+), 65 deletions(-)
-- 2.34.1
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