From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 115950 invoked by alias); 1 Jun 2018 15:30:00 -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 115646 invoked by uid 89); 1 Jun 2018 15:29:32 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,KAM_NUMSUBJECT,SPF_PASS autolearn=no version=3.3.2 spammy= X-HELO: smtp.ispras.ru Date: Fri, 01 Jun 2018 15:30:00 -0000 From: Alexander Monakov To: "H.J. Lu" cc: Leonardo Sandoval , GNU C Library Subject: Re: [PATCH v2] x86-64: Optimize strcmp/wcscmp with AVX2 In-Reply-To: Message-ID: References: <20180529185339.11541-1-leonardo.sandoval.gonzalez@linux.intel.com> User-Agent: Alpine 2.20.13 (LNX 116 2015-12-14) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-SW-Source: 2018-06/txt/msg00010.txt.bz2 On Fri, 1 Jun 2018, H.J. Lu wrote: > Please mention strncmp and wcsncmp in commit subject. OK with this > change. Many Intel CPUs reduce operating frequency upon encountering AVX code, and some have a "spin-up" period when frequency is not yet changed and AVX code runs at reduced throughput. Thus, why is this change not detrimental in practice, doesn't it slow down all code (including other programs running on the same core) as soon as a program makes a call to strcmp? Alexander