From: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org,
bcm-kernel-feedback-list@broadcom.com, kvm@vger.kernel.org,
linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-crypto@vger.kernel.org, linux-csky@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org,
linux-mm@kvack.org, linux-perf-users@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 7/9] lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le}
Date: Sun, 28 Nov 2021 05:56:51 +0100 [thread overview]
Message-ID: <YaMME60Jfiz5BeJF@qmqm.qmqm.pl> (raw)
In-Reply-To: <20211128035704.270739-8-yury.norov@gmail.com>
On Sat, Nov 27, 2021 at 07:57:02PM -0800, Yury Norov wrote:
> Add num_{possible,present,active}_cpus_{eq,gt,le} and replace num_*_cpus()
> with one of new functions where appropriate. This allows num_*_cpus_*()
> to return earlier depending on the condition.
[...]
> @@ -3193,7 +3193,7 @@ int __init pcpu_page_first_chunk(size_t reserved_size,
>
> /* allocate pages */
> j = 0;
> - for (unit = 0; unit < num_possible_cpus(); unit++) {
> + for (unit = 0; num_possible_cpus_gt(unit); unit++) {
This looks dubious. The old version I could hope the compiler would call
num_possible_cpus() only once if it's marked const or pure, but the
alternative is going to count the bits every time making this a guaranteed
O(n^2) even though the bitmap doesn't change.
Best Regards
Michał Mirosław
next prev parent reply other threads:[~2021-11-28 4:58 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YaMME60Jfiz5BeJF@qmqm.qmqm.pl \
--to=mirq-linux@rere.qmqm.pl \
--cc=bcm-kernel-feedback-list@broadcom.com \
--cc=kvm@vger.kernel.org \
--cc=linux-alpha@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-csky@vger.kernel.org \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=yury.norov@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).