From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9987 invoked by alias); 3 Apr 2013 15:08:32 -0000 Mailing-List: contact libc-ports-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: libc-ports-owner@sourceware.org Received: (qmail 9752 invoked by uid 89); 3 Apr 2013 15:08:27 -0000 Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.84/v0.84-167-ge50287c) with ESMTP; Wed, 03 Apr 2013 15:08:27 +0000 Received: from svr-orw-exc-10.mgc.mentorg.com ([147.34.98.58]) by relay1.mentorg.com with esmtp id 1UNPIX-00014j-6I from joseph_myers@mentor.com ; Wed, 03 Apr 2013 08:08:25 -0700 Received: from SVR-IES-FEM-01.mgc.mentorg.com ([137.202.0.104]) by SVR-ORW-EXC-10.mgc.mentorg.com with Microsoft SMTPSVC(6.0.3790.4675); Wed, 3 Apr 2013 08:08:25 -0700 Received: from digraph.polyomino.org.uk (137.202.0.76) by SVR-IES-FEM-01.mgc.mentorg.com (137.202.0.104) with Microsoft SMTP Server id 14.1.289.1; Wed, 3 Apr 2013 16:08:23 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.76) (envelope-from ) id 1UNPIU-0001CM-9L; Wed, 03 Apr 2013 15:08:22 +0000 Date: Wed, 03 Apr 2013 15:08:00 -0000 From: "Joseph S. Myers" To: "Shih-Yuan Lee (FourDollars)" CC: , , , , , Shih-Yuan Lee Subject: Re: [PATCH] ARM: NEON detected memcpy. In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-SW-Source: 2013-04/txt/msg00007.txt.bz2 On Wed, 3 Apr 2013, Shih-Yuan Lee (FourDollars) wrote: > I am working on the NEON detected memcpy. > This is based on what Siarhei Siamashka did at 2009 [1]. I still don't see any copyright assignment on file (whether individual with an employer disclaimer, or corporate) that would cover that work. Without one, we can't use it, and I advise anyone working on NEON memcpy not to look at it. I was previously told by people at ARM that NEON memcpy wasn't a good idea in practice because of raised power consumption, context switch costs etc. from using NEON in processes that otherwise didn't use it, even if it appeared superficially beneficial in benchmarks. -- Joseph S. Myers joseph@codesourcery.com