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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8779AC433FE for ; Sun, 28 Nov 2021 04:59:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230312AbhK1FCN (ORCPT ); Sun, 28 Nov 2021 00:02:13 -0500 Received: from rere.qmqm.pl ([91.227.64.183]:27624 "EHLO rere.qmqm.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229558AbhK1FAL (ORCPT ); Sun, 28 Nov 2021 00:00:11 -0500 Received: from remote.user (localhost [127.0.0.1]) by rere.qmqm.pl (Postfix) with ESMTPSA id 4J1x6D5pcGz4f; Sun, 28 Nov 2021 05:56:52 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=rere.qmqm.pl; s=1; t=1638075413; bh=Ir3YT3zeL32xImHXMHm+HUkV1uXH+xu9Pk/FdYqejaw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qfJt/SEuYDHvacc6G0xjNLwg1Fq717EReqm4qKjJKbJ29nVz4pRzLhvuTEs+OdzmQ YBtV69D9aVFvnRVlMgScH974MXYPVrPlxykIPQGi6nNOPfU8kRQpmThuzgG3a1CYgY 78OZwIEmZp1nYVyJFPH7JKcWetX0Tq4RrwhOe1BNAr0LCbznthHDe87CltKf4hscrH sWADjOEt9FmXj+haWSNMnvon1BnukXnjVIZdfR+TS1YetB95pCqlXSq9QBZTNBbDdH rZ7A1g9OqzSsLIRp6DvBumXPrVPGV6Vae36X2F9VPlEfprs7mm6t+Np5204AGclKvP Nz6Jqvfks862Q== X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.3 at mail Date: Sun, 28 Nov 2021 05:56:51 +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 Content-Transfer-Encoding: 8bit In-Reply-To: <20211128035704.270739-8-yury.norov@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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