RE: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq()

[PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage · Yury Norov <yury.norov@gmail.com> · 2021-11-28
[PATCH 1/9] lib/bitmap: add bitmap_weight_{eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
[PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() · Michał Mirosław <mirq-linux@rere.qmqm.pl> · 2021-11-28
Re: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() · Michał Mirosław <mirq-linux@rere.qmqm.pl> · 2021-11-28
Re: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() · Yury Norov <yury.norov@gmail.com> · 2021-12-14
RE: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() · David Laight <hidden> · 2021-12-15
Re: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() · Yury Norov <yury.norov@gmail.com> · 2021-12-15
[PATCH 3/9] all: replace bitmap_weigth() with bitmap_{empty,full,eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 3/9] all: replace bitmap_weigth() with bitmap_{empty,full,eq,gt,le} · Michał Mirosław <mirq-linux@rere.qmqm.pl> · 2021-11-28
Re: [PATCH 3/9] all: replace bitmap_weigth() with bitmap_{empty,full,eq,gt,le} · Greg Kroah-Hartman <gregkh@linuxfoundation.org> · 2021-11-28
[PATCH 4/9] tools: sync bitmap_weight() usage with the kernel · Yury Norov <yury.norov@gmail.com> · 2021-11-28
[PATCH 5/9] lib/cpumask: add cpumask_weight_{eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
[PATCH 6/9] lib/nodemask: add nodemask_weight_{eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
[PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Michał Mirosław <mirq-linux@rere.qmqm.pl> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Michał Mirosław <mirq-linux@rere.qmqm.pl> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Joe Perches <joe@perches.com> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Dennis Zhou <dennis@kernel.org> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Joe Perches <joe@perches.com> · 2021-11-28
Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} · Emil Renner Berthing <hidden> · 2021-11-28
[PATCH 8/9] lib/nodemask: add num_node_state_eq() · Yury Norov <yury.norov@gmail.com> · 2021-11-28
[PATCH 9/9] MAINTAINERS: add cpumask and nodemask files to BITMAP_API · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage · Nicholas Piggin <npiggin@gmail.com> · 2021-11-28
Re: [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage · Yury Norov <yury.norov@gmail.com> · 2021-11-28
Re: [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage · <hidden> · 2021-11-28
Re: [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage · Yury Norov <yury.norov@gmail.com> · 2021-11-29
Re: [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage · Michał Mirosław <mirq-linux@rere.qmqm.pl> · 2021-11-29
Re: [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage · Yury Norov <yury.norov@gmail.com> · 2021-12-02

From: David Laight <hidden>
Date: 2021-12-15 08:41:11
Also in: kvm, linux-alpha, linux-crypto, linux-perf-users, linux-riscv, linux-s390, linuxppc-dev, lkml

From: Yury Norov

Sent: 14 December 2021 19:43

...

I think that for long bitmaps the most time consuming operation is moving
data to L1, and for short bitmaps the difference between approaches is
barely measurable.

But hweght_long on each iteration can't be more effective than the current
version. So, I'll drop this patch for v2 and keep things unchanged.

Actually do bitmap_full/empty() calls make any sense at all?
The result is stale since bitmaps are designed to do locked operations.
If you have a lock covering the bitmap then you should be using
something that uses non-locked accesses.
Rightly or wrongly that isn't the bitmap api.

	David

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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

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