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 80BB1C433EF for ; Sun, 28 Nov 2021 06:27:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 89F516B0075; Sun, 28 Nov 2021 01:27:40 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 827636B0078; Sun, 28 Nov 2021 01:27:40 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 679C66B007B; Sun, 28 Nov 2021 01:27:40 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0119.hostedemail.com [216.40.44.119]) by kanga.kvack.org (Postfix) with ESMTP id 55A316B0075 for ; Sun, 28 Nov 2021 01:27:40 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 0C26E1846CCF8 for ; Sun, 28 Nov 2021 06:27:30 +0000 (UTC) X-FDA: 78857357460.06.918CF7A Received: from mail-qk1-f179.google.com (mail-qk1-f179.google.com [209.85.222.179]) by imf28.hostedemail.com (Postfix) with ESMTP id A0B4690000A4 for ; Sun, 28 Nov 2021 06:27:29 +0000 (UTC) Received: by mail-qk1-f179.google.com with SMTP id de30so19369278qkb.0 for ; Sat, 27 Nov 2021 22:27:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=UUaWw2/vndQwOuhRc6j6PRwXuBODm2Svdcs9xeM4FlQ=; b=RUU7MzRkdirUtowuDWCiM08P7YQBQBC0acoWzbBj+T+XJI6vVMBSu6aGIKh4+icUwh a8q9bMYJuHCqFTUz0wNigsRNRIbsDwqKoKMNa0qnfF66qijICeNv/dPkbz+/087xhZlV f64hTvJmbUAx1It3pzpI4UUvGtwyNbU+zmtX09eMQ0ByGsuhC27g5T60WwoNMBivtuLQ VUm/Sp71jqGs+1C8GEcrf12fOpYmPWgYxCrrC9gGrggZZRnsjHL5/c7LM3QqhQgnqCqj LxxzrdrvicV7rQvSx7+bgEc8nFcDr55sjaFrS6W7kwXrGHkLvw0E6R41fTx7A36r5Slm hdow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=UUaWw2/vndQwOuhRc6j6PRwXuBODm2Svdcs9xeM4FlQ=; b=i0FYQKbvnYmoMpV/zejuRNVDlqu4KZaPrO4fh6zekq/P2sVzm63LYqZj/sU5lwVDN4 PXnWJC7VZQHUn+mDeiPTA1EzPBxsjgEG2tE1oxMPXegDMZcPxgjeRt1zHIKwVRqPkGQ+ nK9RNsfrl1HfkJkrHOfrCRcWwH0zMz+C1QRUvG3Rp7BrVKexq4vidiW65hs67esqxMgq r8kxidhmS8dz6gzsnNWk8+OpO13iWqam3IDZS5fbXIy641CdcvcZiWJhkAAnZppQCIjF bwgex3ObIz+QaqQrisKIoRFWJNKtHqBr+MeyjlN+5/uUKXQFSTh9IhSt9PZiThyGvSgX sgMQ== X-Gm-Message-State: AOAM5335Ss28/qywNetBEmqz5CR1Wpq3a1kp6fRFf1LfuRVcnyL3G0f3 JuT0VYw2oG3c0Yan4DOXY1s= X-Google-Smtp-Source: ABdhPJxAVXtuKFpo3xQALAgWXmZbnwidtxXikhe9UCcw/0T4+58Z974u1PPCzNdv2+qiERrm5clSCw== X-Received: by 2002:a05:620a:2153:: with SMTP id m19mr32383206qkm.77.1638080848758; Sat, 27 Nov 2021 22:27:28 -0800 (PST) Received: from localhost ([66.216.211.25]) by smtp.gmail.com with ESMTPSA id z4sm6611865qtj.42.2021.11.27.22.27.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 27 Nov 2021 22:27:28 -0800 (PST) Date: Sat, 27 Nov 2021 22:27:27 -0800 From: Yury Norov To: =?utf-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Cc: linux-kernel@vger.kernel.org, "James E.J. Bottomley" , "Martin K. Petersen" , "Paul E. McKenney" , "Rafael J. Wysocki" , Alexander Shishkin , Alexey Klimov , Amitkumar Karwar , Andi Kleen , Andrew Lunn , Andrew Morton , Andy Gross , Andy Lutomirski , Andy Shevchenko , Anup Patel , Ard Biesheuvel , Arnaldo Carvalho de Melo , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christoph Hellwig , Christoph Lameter , Daniel Vetter , Dave Hansen , David Airlie , David Laight , Dennis Zhou , Dinh Nguyen , Geetha sowjanya , Geert Uytterhoeven , Greg Kroah-Hartman , Guo Ren , Hans de Goede , Heiko Carstens , Ian Rogers , Ingo Molnar , Jakub Kicinski , Jason Wessel , Jens Axboe , Jiri Olsa , Jonathan Cameron , Juri Lelli , Kalle Valo , Kees Cook , Krzysztof Kozlowski , Lee Jones , Marc Zyngier , Marcin Wojtas , Mark Gross , Mark Rutland , Matti Vaittinen , Mauro Carvalho Chehab , Mel Gorman , Michael Ellerman , Mike Marciniszyn , Nicholas Piggin , Palmer Dabbelt , Peter Zijlstra , Petr Mladek , Randy Dunlap , Rasmus Villemoes , Roy Pledge , Russell King , Saeed Mahameed , Sagi Grimberg , Sergey Senozhatsky , Solomon Peachy , Stephen Boyd , Stephen Rothwell , Steven Rostedt , Subbaraya Sundeep , Sudeep Holla , Sunil Goutham , Tariq Toukan , Tejun Heo , Thomas Bogendoerfer , Thomas Gleixner , Ulf Hansson , Vincent Guittot , Vineet Gupta , Viresh Kumar , Vivien Didelot , Vlastimil Babka , Will Deacon , 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 2/9] lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq() Message-ID: <20211128062727.GA276670@lapt> References: <20211128035704.270739-1-yury.norov@gmail.com> <20211128035704.270739-3-yury.norov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: A0B4690000A4 X-Stat-Signature: 7gyhtgjy5fserhautacbrkb918tixbje Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=RUU7MzRk; spf=pass (imf28.hostedemail.com: domain of yury.norov@gmail.com designates 209.85.222.179 as permitted sender) smtp.mailfrom=yury.norov@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1638080849-419354 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 05:37:19AM +0100, Micha=C5=82 Miros=C5=82aw wrote= : > On Sat, Nov 27, 2021 at 07:56:57PM -0800, Yury Norov wrote: > > Now as we have bitmap_weight_eq(), switch bitmap_full() and > > bitmap_empty() to using it. > [...] > > -static inline bool bitmap_empty(const unsigned long *src, unsigned n= bits) > > -{ > > - if (small_const_nbits(nbits)) > > - return ! (*src & BITMAP_LAST_WORD_MASK(nbits)); > > - > > - return find_first_bit(src, nbits) =3D=3D nbits; > > -} > [...] > > +static __always_inline bool bitmap_empty(const unsigned long *src, u= nsigned int nbits) > > +{ > > + return bitmap_weight_eq(src, nbits, 0); > > +} > [..] >=20 > What's the speed difference? Have you benchmarked this? bitmap_weight_eq() should be faster than find_first_bit(), but the difference is few cycles, so I didn't bother measuring it. New version looks just better.