From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id C9A201F462 for ; Wed, 22 May 2019 11:28:18 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:cc:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; q=dns; s=default; b=xlX1LQtr3dEhk4s4 jWCQb4sB8gxPHsuI96+ziwHabOhOmqKDehPaqVp2YQHQKSaD9qosYIBVR5g5RN+B GDFdpbIrPmSVedD8ecQVU6qOkuneIJszjKgSXDtP8kXUP6iMrtXFp9Fq6/TOzg4+ 0eKPt6/ga0Wu3SiYIAn2pWeq1MI= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:cc:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; s=default; bh=gPJCJw3KA7LAfCV+GtjZUx a/c3Y=; b=tszVyEm3p/FX1pMDeslsJH5S2TPEMU47dUbmlUaJri3IZ1N6B0fNvi 2/ydTjFl9w3usH6iZPk6yd/hLuktqK4S+3jijy2frcKV8Yyl2LQ+3/Uy3isy5Q1F 3xCwL2sqWMc258yTDAJiOKfeMmdC42zDzFSB2MyW5BqnwfUlek0Vk= Received: (qmail 75415 invoked by alias); 22 May 2019 11:28:16 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 75404 invoked by uid 89); 22 May 2019 11:28:16 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: bisque.maple.relay.mailchannels.net X-Sender-Id: dreamhost|x-authsender|siddhesh@gotplt.org X-Sender-Id: dreamhost|x-authsender|siddhesh@gotplt.org X-MC-Relay: Neutral X-MailChannels-SenderId: dreamhost|x-authsender|siddhesh@gotplt.org X-MailChannels-Auth-Id: dreamhost X-Bottle-Attack: 048aad2a55869fd7_1558524492190_2394660876 X-MC-Loop-Signature: 1558524492189:4109763810 X-MC-Ingress-Time: 1558524492189 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=gotplt.org; h=subject:to :cc:references:from:message-id:date:mime-version:in-reply-to :content-type:content-transfer-encoding; s=gotplt.org; bh=gPJCJw 3KA7LAfCV+GtjZUxa/c3Y=; b=BRy7ik4e2JqmeBaipE9veeU11rpM0JGOH+hWti 7uCwZpBx1wOfeoVLsHFCQSP9gPVE9bkacC2hta5AZYgqeVETINhDgBGaYDqn5fFz Xdr4eNc9qnZkK16rRz4957AQRaXDVfTasev2v7cqpTz2Ljj+kCiOjt8UxMEEQrk/ v/IXo= Subject: Re: [PATCH] Improve string benchtest timing To: Wilco Dijkstra , Adhemerval Zanella , "libc-alpha@sourceware.org" Cc: nd References: <3acd7a7f-c06a-6679-d526-e758d9ff30ab@gotplt.org> X-DH-BACKEND: pdx1-sub0-mail-a25 From: Siddhesh Poyarekar Openpgp: preference=signencrypt Message-ID: <11d4661e-914d-237b-c2db-c9ef4739460d@gotplt.org> Date: Wed, 22 May 2019 16:57:57 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-VR-OUT-STATUS: OK X-VR-OUT-SCORE: -100 X-VR-OUT-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeduuddrudduvddggedtucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuggftfghnshhusghstghrihgsvgdpffftgfetoffjqffuvfenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhepuffvfhfhkffffgggjggtgfesthejredttdefjeenucfhrhhomhepufhiugguhhgvshhhucfrohihrghrvghkrghruceoshhiugguhhgvshhhsehgohhtphhlthdrohhrgheqnecukfhppedutdefrdduleelrddujeefrddvjeenucfrrghrrghmpehmohguvgepshhmthhppdhhvghloheplgdutddrtddrtddrudehngdpihhnvghtpedutdefrdduleelrddujeefrddvjedprhgvthhurhhnqdhprghthhepufhiugguhhgvshhhucfrohihrghrvghkrghruceoshhiugguhhgvshhhsehgohhtphhlthdrohhrgheqpdhmrghilhhfrhhomhepshhiugguhhgvshhhsehgohhtphhlthdrohhrghdpnhhrtghpthhtohephghilhgtohdrffhijhhkshhtrhgrsegrrhhmrdgtohhmnecuvehluhhsthgvrhfuihiivgeptd On 22/05/19 4:41 PM, Wilco Dijkstra wrote: > Well if I force the copies to be mutually unaligned, there is only about 1% difference > for a few of the memcpy implementations compared to them being always aligned > The others show identical performance whether aligned or not. This is not too > surprising since the test is basically waiting for DRAM most of the time. That's a good point. Is that the case for thunderx as well? IIRC they perform particularly badly with misaligned code but I don't know if they're bad enough to be significant in the face of DRAM waits. > So if we wanted to measure something useful we'd need to do it differently. Maybe > the goal was to measure DRAM bandwidth? If so we could modify it to compare > copy bandwidth for just a few different sizes (corresponding with typical L1/L2/L3 sizes). That sounds like a good idea. Siddhesh