From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 83498 invoked by alias); 18 Apr 2017 19:08:44 -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 83489 invoked by uid 89); 18 Apr 2017 19:08:43 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy= X-HELO: mx1.redhat.com DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 18ACF19CF73 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=fweimer@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 18ACF19CF73 Subject: Re: [PATCH] x86: Use AVX2 memcpy/memset on Skylake server [BZ #21396] To: "H.J. Lu" References: <20170418183712.GA22211@intel.com> Cc: libc-alpha@sourceware.org From: Florian Weimer Message-ID: Date: Tue, 18 Apr 2017 19:08:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.0 MIME-Version: 1.0 In-Reply-To: <20170418183712.GA22211@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2017-04/txt/msg00327.txt.bz2 On 04/18/2017 08:37 PM, H.J. Lu wrote: > On Skylake server, AVX512 load/store instructions in memcpy/memset may > lead to lower CPU turbo frequency in certain situations. Use of AVX2 > in memcpy/memset has been observed to have improved overall performance > in many workloads due to the higher frequency. Since you bring this up: I think I have read reports that this happens with AVX2 and some parts, too. The change itself looks reasonable. Thanks, Florian