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[209.85.208.178]) by smtp.gmail.com with ESMTPSA id y2sm260005lfe.242.2021.09.08.11.34.43 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Sep 2021 11:34:44 -0700 (PDT) Received: by mail-lj1-f178.google.com with SMTP id m4so5052406ljq.8 for ; Wed, 08 Sep 2021 11:34:43 -0700 (PDT) X-Received: by 2002:a2e:8185:: with SMTP id e5mr3781033ljg.31.1631126083674; Wed, 08 Sep 2021 11:34:43 -0700 (PDT) MIME-Version: 1.0 References: <20210907195226.14b1d22a07c085b22968b933@linux-foundation.org> <20210908025845.cwXLsq_Uo%akpm@linux-foundation.org> In-Reply-To: <20210908025845.cwXLsq_Uo%akpm@linux-foundation.org> From: Linus Torvalds Date: Wed, 8 Sep 2021 11:34:27 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 103/147] lib/string: optimized memset To: Andrew Morton Cc: David Laight , drew@beagleboard.org, Guo Ren , Christoph Hellwig , kernel@esmil.dk, Linux-MM , mcroce@microsoft.com, mick@ics.forth.gr, mm-commits@vger.kernel.org, Nick Desaulniers , Palmer Dabbelt Content-Type: text/plain; charset="UTF-8" Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org I'm dropping this one just to be consistent, although for memset() it's possibly a bit more reasonable to fall back on some default. But probably not. memcpy and memset really are *so* special that these generic versions should be considered to be "stupid placeholders for bringup, and nothing more". On Tue, Sep 7, 2021 at 7:58 PM Andrew Morton wrote: > > On a RISC-V machine the speed goes from 140 Mb/s to 241 Mb/s, and this the > binary size increase according to bloat-o-meter: I also react to the benchmark numbers: RISC-V already has #define __HAVE_ARCH_MEMSET #define __HAVE_ARCH_MEMCPY #define __HAVE_ARCH_MEMMOVE in its file, so these are just odd. Did you benchmark these generic functions on their own, rather than the ones that actually get *used*? Linus 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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2806C433F5 for ; Wed, 8 Sep 2021 18:34:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5F6BE61153 for ; Wed, 8 Sep 2021 18:34:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5F6BE61153 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id E4857900002; Wed, 8 Sep 2021 14:34:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DF81E6B0072; Wed, 8 Sep 2021 14:34:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CE5F4900002; Wed, 8 Sep 2021 14:34:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0088.hostedemail.com [216.40.44.88]) by kanga.kvack.org (Postfix) with ESMTP id BC0356B0071 for ; Wed, 8 Sep 2021 14:34:47 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 64B9B182DA429 for ; Wed, 8 Sep 2021 18:34:47 +0000 (UTC) X-FDA: 78565257414.21.401925A Received: from mail-lf1-f49.google.com (mail-lf1-f49.google.com [209.85.167.49]) by imf14.hostedemail.com (Postfix) with ESMTP id 1E5976001983 for ; Wed, 8 Sep 2021 18:34:47 +0000 (UTC) Received: by mail-lf1-f49.google.com with SMTP id s10so6233334lfr.11 for ; Wed, 08 Sep 2021 11:34:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=aMVIkkBfSE2tqSN2Teaj0GxByK6w+qQQR/o0rQOZufU=; b=VsJ85LZphyoafBljbFM8vktNbehdKKjmmvYeX4kr1mqe1OVePjWHmDyKS9lRzXBaEg ekBhojeOvDY2YwAusYQGXvZfQd5vAvYetuf5FOQ1i6e6Ou1Zmg36s4kJtNPxPeCtJf8B ppFdYZwYE5h2GRyLaXDAHduyLfzhU0aK2G3rw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=aMVIkkBfSE2tqSN2Teaj0GxByK6w+qQQR/o0rQOZufU=; b=zcfZvflIua/Veco3uHU7Bq0R+dFULPp/ifLfuyeMs6FWwFUghrC36MlzZ3ebDHQZp0 ul/D1qVGVKSuudFnnsFO50NQqgO5heTeX0DyMkYs+J313SBuPfIbLV5gQSRPs6tCBnd9 yB6EynS0/y+sT6RstBbyUq/IGIF6vWILQUj9YYgAfZVI++2qlLVD1R8xvxt+L2dcwP6S DgA98yTbYE5jSl7F8huHRlOLdTN3BgrTh/3FoyQzTRsiSlASZh6RaTZCMh07Vvs0S1dR EZa0lbvqboaOFd8nOJyPJZFgNmU4ULSIFutkalA2MAQIjBF2WcmagDcjJX7QfTnHStue qXLA== X-Gm-Message-State: AOAM531voFvxiEt3bWKbD2/y65nCRo5qQXRzx9r+EbjKpAvgRQNrO0id IlF6hdLv3fXCN8cHAb9/jQP2XfhTFCcu+FpzqVA= X-Google-Smtp-Source: ABdhPJx2mbNo4ORFcUJSZfq4i8PqPDJqvXaHDvV80IFS5OGB+SLZqDE+tVf1lM2OlfrkDCIyb6s3dg== X-Received: by 2002:a19:384e:: with SMTP id d14mr3522040lfj.114.1631126085260; Wed, 08 Sep 2021 11:34:45 -0700 (PDT) Received: from mail-lj1-f177.google.com (mail-lj1-f177.google.com. [209.85.208.177]) by smtp.gmail.com with ESMTPSA id h21sm259568lfv.273.2021.09.08.11.34.43 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Sep 2021 11:34:44 -0700 (PDT) Received: by mail-lj1-f177.google.com with SMTP id s3so5038156ljp.11 for ; Wed, 08 Sep 2021 11:34:43 -0700 (PDT) X-Received: by 2002:a2e:8185:: with SMTP id e5mr3781033ljg.31.1631126083674; Wed, 08 Sep 2021 11:34:43 -0700 (PDT) MIME-Version: 1.0 References: <20210907195226.14b1d22a07c085b22968b933@linux-foundation.org> <20210908025845.cwXLsq_Uo%akpm@linux-foundation.org> In-Reply-To: <20210908025845.cwXLsq_Uo%akpm@linux-foundation.org> From: Linus Torvalds Date: Wed, 8 Sep 2021 11:34:27 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 103/147] lib/string: optimized memset To: Andrew Morton Cc: David Laight , drew@beagleboard.org, Guo Ren , Christoph Hellwig , kernel@esmil.dk, Linux-MM , mcroce@microsoft.com, mick@ics.forth.gr, mm-commits@vger.kernel.org, Nick Desaulniers , Palmer Dabbelt Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1E5976001983 Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=VsJ85LZp; dmarc=none; spf=pass (imf14.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.167.49 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org X-Stat-Signature: 7gbsstyysxxr57t9frhb1wqdok86p33g X-HE-Tag: 1631126087-353093 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: I'm dropping this one just to be consistent, although for memset() it's possibly a bit more reasonable to fall back on some default. But probably not. memcpy and memset really are *so* special that these generic versions should be considered to be "stupid placeholders for bringup, and nothing more". On Tue, Sep 7, 2021 at 7:58 PM Andrew Morton wrote: > > On a RISC-V machine the speed goes from 140 Mb/s to 241 Mb/s, and this the > binary size increase according to bloat-o-meter: I also react to the benchmark numbers: RISC-V already has #define __HAVE_ARCH_MEMSET #define __HAVE_ARCH_MEMCPY #define __HAVE_ARCH_MEMMOVE in its file, so these are just odd. Did you benchmark these generic functions on their own, rather than the ones that actually get *used*? Linus