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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D4A78C433F5 for ; Sun, 28 Nov 2021 07:04:38 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4J1zxc6140z3cTj for ; Sun, 28 Nov 2021 18:04:36 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20210112 header.b=RUU7MzRk; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gmail.com (client-ip=2607:f8b0:4864:20::72c; helo=mail-qk1-x72c.google.com; envelope-from=yury.norov@gmail.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20210112 header.b=RUU7MzRk; dkim-atps=neutral Received: from mail-qk1-x72c.google.com (mail-qk1-x72c.google.com [IPv6:2607:f8b0:4864:20::72c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4J1z6s2KwFz30RH for ; Sun, 28 Nov 2021 17:27:32 +1100 (AEDT) Received: by mail-qk1-x72c.google.com with SMTP id i9so19331803qki.3 for ; Sat, 27 Nov 2021 22:27:32 -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=rgSJUTU4BIoziCc/NDxhVD3s9hw2FPh6Qc9F5V9Go8JdjpjbTghfzy7qts1uESyfQK cv7kw4vncJ658hAbJe3VRmpXApNUI8CC2K8/80ahZoD0fuXuaY1T7XDSGET2hN7JqR71 aInAWu+uLC/aCt+jk+CJcrAVstRzptaiRiAI5rvtcjl8b6mE+a5lQA2ay/1wkk0fC2CH +WmSQirb8JKU7CtkC5CTai5CEQAAqK3cepMyHy63kZ/adIX6nMhMNLiFFOIPlc6PgVW9 KRKi0/USmM5mEOEJrg/0riSlXYwquWuwEERmtovoNLWbZiwoJKqcA2uwtvIirx1XUY++ hc9A== X-Gm-Message-State: AOAM533kFsMq8lYRHE36ap6VGIMR80siZOJVtNipcC83yjfdIlZrnasO l7kDeoHfrrXoSJqJm04s0gg= 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=?= 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 Content-Transfer-Encoding: 8bit In-Reply-To: X-Mailman-Approved-At: Sun, 28 Nov 2021 18:04:00 +1100 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Andrew Lunn , "Rafael J. Wysocki" , Catalin Marinas , Guo Ren , Christoph Lameter , Christoph Hellwig , Andi Kleen , Vincent Guittot , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Viresh Kumar , Petr Mladek , Arnaldo Carvalho de Melo , Jens Axboe , Andy Lutomirski , Lee Jones , Greg Kroah-Hartman , Randy Dunlap , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Sergey Senozhatsky , Thomas Gleixner , linux-crypto@vger.kernel.org, Tejun Heo , Andrew Morton , Mark Rutland , Anup Patel , linux-ia64@vger.kernel.org, David Airlie , Roy Pledge , Dave Hansen , Solomon Peachy , Stephen Rothwell , Krzysztof Kozlowski , Dennis Zhou , Matti Vaittinen , linux-alpha@vger.kernel.org, Kalle Valo , Stephen Boyd , Tariq Toukan , Dinh Nguyen , Jonathan Cameron , Ulf Hansson , Alexander Shishkin , Mike Marciniszyn , Rasmus Villemoes , Subbaraya Sundeep , Will Deacon , Sagi Grimberg , linux-csky@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, linux-arm-kernel@lists.infradead.org, linux-snps-arc@lists.infradead.org, Kees Cook , Arnd Bergmann , "James E.J. Bottomley" , Vineet Gupta , Steven Rostedt , Mark Gross , Borislav Petkov , Mauro Carvalho Chehab , Thomas Bogendoerfer , "Martin K. Petersen" , David Laight , Sudeep Holla , Geetha sowjanya , Ian Rogers , kvm@vger.kernel.org, Peter Zijlstra , Amitkumar Karwar , linux-mm@kvack.org, linux-riscv@lists.infradead.org, Jiri Olsa , Ard Biesheuvel , Marc Zyngier , Russell King , Andy Gross , Jakub Kicinski , Vivien Didelot , Sunil Goutham , "Paul E. McKenney" , linux-s390@vger.kernel.org, Alexey Klimov , Heiko Carstens , Hans de Goede , Nicholas Piggin , Marcin Wojtas , Vlastimil Babka , linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org, Palmer Dabbelt , Daniel Vetter , Jason Wessel , Saeed Mahameed , Andy Shevchenko Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Nov 28, 2021 at 05:37:19AM +0100, Michał Mirosław 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 nbits) > > -{ > > - if (small_const_nbits(nbits)) > > - return ! (*src & BITMAP_LAST_WORD_MASK(nbits)); > > - > > - return find_first_bit(src, nbits) == nbits; > > -} > [...] > > +static __always_inline bool bitmap_empty(const unsigned long *src, unsigned int nbits) > > +{ > > + return bitmap_weight_eq(src, nbits, 0); > > +} > [..] > > 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.