From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 6429 invoked by alias); 13 Dec 2013 04:40:37 -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 6418 invoked by uid 89); 13 Dec 2013 04:40:36 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.1 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 13 Dec 2013 04:40:34 +0000 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id rBD4eIjA029949 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Thu, 12 Dec 2013 23:40:21 -0500 Received: from [10.3.113.84] (ovpn-113-84.phx2.redhat.com [10.3.113.84]) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id rBD4eG6s011329; Thu, 12 Dec 2013 23:40:17 -0500 Message-ID: <52AA8FAF.5070606@redhat.com> Date: Fri, 13 Dec 2013 04:40:00 -0000 From: "Carlos O'Donell" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Steve Ellcey , "Carlos O'Donell" CC: Andrew Pinski , "Joseph S. Myers" , "libc-ports@sourceware.org" Subject: Re: [patch, mips] Improved memset for MIPS References: <93a232b5-9d0b-4a27-bbb5-16e3ae7c4b89@BAMAIL02.ba.imgtec.org> <1378483039.5770.302.camel@ubuntu-sellcey> <1378486241.5770.327.camel@ubuntu-sellcey> <1379526035.5770.414.camel@ubuntu-sellcey> <1379698355.5770.466.camel@ubuntu-sellcey> <1386893669.2764.30.camel@ubuntu-sellcey> In-Reply-To: <1386893669.2764.30.camel@ubuntu-sellcey> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2013-12/txt/msg00016.txt.bz2 On 12/12/2013 07:14 PM, Steve Ellcey wrote: > On Thu, 2013-12-12 at 19:01 -0500, Carlos O'Donell wrote: > >>> I noticed this patch causes some performance regressions on Octeon due >>> to having 128 byte cache lines. >>> Changing PREFETCH_CHUNK/PREFETCH_FOR_STORE to assume 128 byte cache >>> line gives us the performance back and improves over the original code >>> at least 15%. >>> That is: >>> # define PREFETCH_CHUNK 128 >>> # define PREFETCH_FOR_STORE(chunk, reg) \ >>> pref PREFETCH_STORE_HINT, (chunk)*128(reg); >> >> Submit a patch for that? >> >> We have microbenchmarks now, but the next hardest >> part is going to be archiving data by device so that >> the community can help track performance and point >> out regressions like this. >> >> Cheers, >> Carlos. > > Unless the change is under some kind of ifdef for Octeon changing this > will probably slow down other MIPS chips. Most of them have 32 byte > cache lines. Absolutely. I don't suggest he just change it, but Andrew would have to add enough framework for Octeon to be enabled with an optimal implementation. For example you could compile an alternate version with 128 byte cache line support and select it via IFUNC based on AT_HWCAP? Cheers, Carlos.