From owner-dev-commits-src-main@freebsd.org Mon Feb 8 19:36:45 2021 Return-Path: Delivered-To: dev-commits-src-main@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id E577553E871 for ; Mon, 8 Feb 2021 19:36:45 +0000 (UTC) (envelope-from jrtc27@jrtc27.com) Received: from mail-wr1-f45.google.com (mail-wr1-f45.google.com [209.85.221.45]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4DZGVj5xJjz4k3F for ; Mon, 8 Feb 2021 19:36:45 +0000 (UTC) (envelope-from jrtc27@jrtc27.com) Received: by mail-wr1-f45.google.com with SMTP id g6so5629067wrs.11 for ; Mon, 08 Feb 2021 11:36:45 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=O81UVmBRD1JcxFCvYm5cyLv3yKY72WYggDRlAi/+jPw=; b=NfjYQmrzFZhWiOHusicpUNz/9S68Ed2KnV7Wiq3ao8fJnZULeDR3W5rGHR7iZ77H92 bTnRVSed4L2PCjE5228iWjcqoui1eWU+XYN9bNFKd+joMF6zavo67EG02kbnbDA0zgTM fl3TtIS+YYCKUDAdbd6i54NkfT7hSzsFkVz8R2ZhIhXVgBent6CrzLrd/YtKrGjBlzkD pJ+Bl1L+WVvRGmt5wFFmYVXH4wp2zslT3erkZzXptn4+CVYMBdq6g+lwv4aMlmnySUON nRf53Gsj0sEKiurLg8L7bUI7T+g2wklLKOdX4KoRh2LK3UH2bSSbdIcaJQfy+EwYjE+s HRVg== X-Gm-Message-State: AOAM530XFKwqeHi4rLuvagfuFQvcdIk96/ywoC7XyCwLggQIOgRH1K22 I+PcONhr9KRSCJHcn3bWnLK7OA== X-Google-Smtp-Source: ABdhPJzIDKEvEXZ/TWBvng29nekyUkt9zhS60eZL/b3SoYTdY7cEH3vWHGh5flRnVKjhBA9j9uwmrA== X-Received: by 2002:a05:6000:1565:: with SMTP id 5mr22006701wrz.109.1612813004393; Mon, 08 Feb 2021 11:36:44 -0800 (PST) Received: from [192.168.149.251] (trinity-students-nat.trin.cam.ac.uk. [131.111.193.104]) by smtp.gmail.com with ESMTPSA id w15sm29538756wrp.15.2021.02.08.11.36.43 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 08 Feb 2021 11:36:43 -0800 (PST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.4\)) Subject: Re: git: af366d353b84 - main - amd64: implement strlen in assembly From: Jessica Clarke In-Reply-To: <202102081915.118JFXkJ067892@gitrepo.freebsd.org> Date: Mon, 8 Feb 2021 19:36:42 +0000 Cc: "src-committers@freebsd.org" , "dev-commits-src-all@freebsd.org" , "dev-commits-src-main@freebsd.org" Content-Transfer-Encoding: quoted-printable Message-Id: <3E64387A-42DD-4470-8893-5B774F19754E@freebsd.org> References: <202102081915.118JFXkJ067892@gitrepo.freebsd.org> To: Mateusz Guzik X-Mailer: Apple Mail (2.3608.120.23.2.4) X-Rspamd-Queue-Id: 4DZGVj5xJjz4k3F X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-BeenThere: dev-commits-src-main@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commit messages for the main branch of the src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Feb 2021 19:36:46 -0000 On 8 Feb 2021, at 19:15, Mateusz Guzik wrote: >=20 > The branch main has been updated by mjg: >=20 > URL: = https://cgit.FreeBSD.org/src/commit/?id=3Daf366d353b84bdc4e730f0fc563853ab= c338271c >=20 > commit af366d353b84bdc4e730f0fc563853abc338271c > Author: Mateusz Guzik > AuthorDate: 2021-02-08 17:01:48 +0000 > Commit: Mateusz Guzik > CommitDate: 2021-02-08 19:15:21 +0000 >=20 > amd64: implement strlen in assembly >=20 > The C variant in libkern performs excessive branching to find the > non-zero byte instead of using the bsfq instruction. The same code > patched to use it is still slower than the routine implemented here > as the compiler keeps neglecting to perform certain optimizations > (like using leaq). >=20 > On top of that the routine can is a starting point for copyinstr > which operates on words instead of bytes. >=20 > Tested with glibc test suite. >=20 > Sample results (calls/s): >=20 > Haswell: > $(perl -e "print 'A' x 3"): > stock: 211198039 > patched:338626619 > asm: 465609618 >=20 > $(perl -e "print 'A' x 100"): > stock: 83151997 > patched: 98285919 > asm: 120719888 >=20 > AMD EPYC 7R32: > $(perl -e "print 'A' x 3"): > stock: 282523617 > asm: 491498172 >=20 > $(perl -e "print 'A' x 100"): > stock: 114857172 > asm: 112082057 No Reviewed by? More than one pair of eyes on non-trivial assembly is almost always a good idea. Jess