From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 54909 invoked by alias); 25 May 2017 16:43:26 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 54894 invoked by uid 89); 25 May 2017 16:43:25 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,RCVD_IN_SORBS_SPAM,SPF_PASS autolearn=no version=3.3.2 spammy=Hx-languages-length:1259 X-HELO: mail-pf0-f182.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=/og+Ao5+3yhWZYgkQxFOzIJeCMQCFbPIPuSHZyUeamg=; b=a1hUqu/T6v9z+5lKP8yv00edHb76Y3HXBGoiG6B86OvxrU8rOtnDqgTqB6miriMqDl VwkYXQII3u0oxcnxyx+wXZUSNpkOHQYT91eQxCLIZEmos9h60FtbAXoE1fwmDwC8TDcn QUZ/UzUGZeWfJZMU8s3ZCILkoXVGmOjyhfmwCeCEYVIH5z6gPanEZQ52p61TRyuauTHz CopWUuKK4kt+bHIYMgHhUM7tEIA1+qVpTsSn53NPouahhtpmzqianXTlTQb/Qx47AbaX diUk84tHu6Ch7pOrPta33OJkmnLLcFlKtW+RNwtEiZh9bIZS4QSIDblQWXPuzU463Rqm Ud1A== X-Gm-Message-State: AODbwcCflFurdYc1wLuOg7jwVkGSbQN6CxNzLwngyvM5n8L1M1Z3+T9d 9HiQNB974vHSlR0l/uCUHsJHqiTbjw== X-Received: by 10.84.184.12 with SMTP id l12mr52769260plc.9.1495730606769; Thu, 25 May 2017 09:43:26 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1493663254.29498.11.camel@cavium.com> <5909E2C5.7090603@arm.com> <1494366305.9224.26.camel@cavium.com> <74006e0a-fb4a-dc36-bc29-77303cef3cfb@gotplt.org> <5925BD04.7000902@arm.com> <0950612b-cff4-2256-6f81-3bacf30ce7e9@gotplt.org> From: Ramana Radhakrishnan Date: Thu, 25 May 2017 16:43:00 -0000 Message-ID: Subject: Re: Ping: [Patch] aarch64: Thunderx specific memcpy and memmove To: Andrew Pinski Cc: Siddhesh Poyarekar , Szabolcs Nagy , "Ellcey, Steve" , libc-alpha , Wilco Dijkstra , nd Content-Type: text/plain; charset="UTF-8" X-SW-Source: 2017-05/txt/msg00762.txt.bz2 On Thu, May 25, 2017 at 5:28 PM, Andrew Pinski wrote: > On Wed, May 24, 2017 at 11:42 PM, Siddhesh Poyarekar > wrote: >> On Wednesday 24 May 2017 10:34 PM, Szabolcs Nagy wrote: >>> - i don't know if you plan to make more changes to the thunderx >>> memcpy, if prefetching is the only change then it's likely that >>> we can agree on a generic version that's good enough. if you >>> do plan to make further changes, then keep in mind that we try >>> to have same/similar generic memcpy across c runtimes and if >>> your change is good for generic we might not be able to use the >>> code outside of glibc (so newlib, bionic, freebsd,.. memcpy >>> would diverge) >> >> Steve, if that is desirable then please consider contributing the code >> to cortex-strings[1]. > > One memcpy does not fit all micro-arch. Just look at x86, where they > have many different versions and even do selection based on cache size > (see the current discussion about the memcpy regression). No it doesn't but that's not an excuse for putting in multiple copies without the engineering to see if generic memcpy's are improved. Otherwise it's just bloatware. regards Ramana