From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6EA9C433EF for ; Sun, 28 Nov 2021 05:10:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 308A76B0075; Sun, 28 Nov 2021 00:10:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B83F6B0078; Sun, 28 Nov 2021 00:10:08 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 17F866B007B; Sun, 28 Nov 2021 00:10:08 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0203.hostedemail.com [216.40.44.203]) by kanga.kvack.org (Postfix) with ESMTP id 05A3E6B0075 for ; Sun, 28 Nov 2021 00:10:08 -0500 (EST) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id AEBCD1830D199 for ; Sun, 28 Nov 2021 05:09:57 +0000 (UTC) X-FDA: 78857162034.08.DD2A96F Received: from rere.qmqm.pl (rere.qmqm.pl [91.227.64.183]) by imf11.hostedemail.com (Postfix) with ESMTP id 4C948F0000B5 for ; Sun, 28 Nov 2021 05:09:57 +0000 (UTC) Received: from remote.user (localhost [127.0.0.1]) by rere.qmqm.pl (Postfix) with ESMTPSA id 4J1xPH1FPPz4f; Sun, 28 Nov 2021 06:09:55 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=rere.qmqm.pl; s=1; t=1638076195; bh=oUZYFQUmcrcLe+khMfxoyii9jHAFHFy8/qX4bg6ScHU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JnSDJhb2/wFE1+K5BEKj3l92hAUJYMSiQfvzp+ZlCATcD11ALuloHBV8agVwt/D5m 6xO5KVkS6ds9BhnvUIzgpE+GOAlwIHTeHWZUDQLRlCqXrEtKOnOW/XLCrUHjRtkpA+ s0Zgh/IC7vC3LAsHBRaM+HBKV7zFjzE+7UOTFGbokGiHbpHQX7rXsKsJST3S+JBeda 2sNRV1hDCglR6IzM+jk8O4GqGLON53RjQjMI9dzQcjIf9OmuQDCgevPa74eYKb6N8i DO41zxtTZnaEDqhBVPy9rAwcuQc/n0JQGJK3acFZNX84ZqpVMLYjA4M2TxieYk4Vj5 b6s4KzCtg6yrQ== X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.3 at mail Date: Sun, 28 Nov 2021 06:09:53 +0100 From: =?iso-8859-2?Q?Micha=B3_Miros=B3aw?= To: Yury Norov 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} Message-ID: References: <20211128035704.270739-1-yury.norov@gmail.com> <20211128035704.270739-8-yury.norov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-2 Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 4C948F0000B5 X-Stat-Signature: 9q6x87x5u83twz5ay4r3cx6j5siorju3 Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=rere.qmqm.pl header.s=1 header.b=JnSDJhb2; dmarc=pass (policy=reject) header.from=rere.qmqm.pl; spf=pass (imf11.hostedemail.com: domain of mirq-linux@rere.qmqm.pl designates 91.227.64.183 as permitted sender) smtp.mailfrom=mirq-linux@rere.qmqm.pl X-Rspamd-Server: rspam02 X-HE-Tag: 1638076197-453158 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Nov 28, 2021 at 05:56:51AM +0100, Micha=B3 Miros=B3aw wrote: > 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_*_c= pus() > > 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 reserve= d_size, > > =20 > > /* allocate pages */ > > j =3D 0; > > - for (unit =3D 0; unit < num_possible_cpus(); unit++) { > > + for (unit =3D 0; num_possible_cpus_gt(unit); unit++) { >=20 > This looks dubious. The old version I could hope the compiler would cal= l > 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 guarant= eed > O(n^2) even though the bitmap doesn't change. Hmm. This code already unnecessarily calls num_possible_cpus() multiple times. Since it doesn't change after early init I would suggest just calling it once here. Best Regards Micha=B3=A0Miros=B3aw