From: David Laight <David.Laight@ACULAB.COM>
To: "'Yury Norov'" <yury.norov@gmail.com>,
"Michał Mirosław" <mirq-linux@rere.qmqm.pl>
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Subject: RE: [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq()
Date: Wed, 15 Dec 2021 08:40:10 +0000 [thread overview]
Message-ID: <0ccb827de1164b2989d652bfb6f1bbab@AcuMS.aculab.com> (raw)
In-Reply-To: <CAAH8bW9-dbENFUrwPUQ-uJVVX_s=PWb2zpAJ8BqkV3vJE696mA@mail.gmail.com>
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
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2021-12-15 8:41 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-28 3:56 [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage Yury Norov
2021-11-28 3:56 ` [PATCH 1/9] lib/bitmap: add bitmap_weight_{eq,gt,le} Yury Norov
2021-11-28 3:56 ` [PATCH 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() Yury Norov
2021-11-28 4:37 ` Michał Mirosław
2021-11-28 6:27 ` Yury Norov
2021-11-28 18:10 ` Michał Mirosław
2021-12-14 19:43 ` Yury Norov
2021-12-15 8:40 ` David Laight [this message]
2021-12-15 17:45 ` Yury Norov
2021-11-28 3:56 ` [PATCH 3/9] all: replace bitmap_weigth() with bitmap_{empty,full,eq,gt,le} Yury Norov
2021-11-28 4:47 ` Michał Mirosław
2021-11-28 8:01 ` Greg Kroah-Hartman
2021-11-28 3:56 ` [PATCH 4/9] tools: sync bitmap_weight() usage with the kernel Yury Norov
2021-11-28 3:57 ` [PATCH 5/9] lib/cpumask: add cpumask_weight_{eq,gt,le} Yury Norov
2021-11-28 3:57 ` [PATCH 6/9] lib/nodemask: add nodemask_weight_{eq,gt,le} Yury Norov
2021-11-28 3:57 ` [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le} Yury Norov
2021-11-28 4:56 ` Michał Mirosław
2021-11-28 5:09 ` Michał Mirosław
2021-11-28 6:34 ` Yury Norov
2021-11-28 17:07 ` Joe Perches
2021-11-28 17:43 ` Yury Norov
2021-11-28 17:54 ` Dennis Zhou
2021-11-28 18:47 ` Yury Norov
2021-11-28 17:56 ` Emil Renner Berthing
2021-11-28 17:57 ` Joe Perches
2021-11-28 3:57 ` [PATCH 8/9] lib/nodemask: add num_node_state_eq() Yury Norov
2021-11-28 3:57 ` [PATCH 9/9] MAINTAINERS: add cpumask and nodemask files to BITMAP_API Yury Norov
2021-11-28 11:08 ` [PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage Nicholas Piggin
2021-11-28 23:36 ` Yury Norov
2021-11-28 18:03 ` mirq-test
2021-11-28 18:05 ` Michał Mirosław
2021-11-29 6:38 ` Yury Norov
2021-11-29 16:34 ` Michał Mirosław
2021-12-02 0:31 ` Yury Norov
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