From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 58583 invoked by alias); 16 Aug 2017 14:26:32 -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 49006 invoked by uid 89); 16 Aug 2017 14:26:27 -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,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.2 spammy=Ven X-HELO: homiemail-a122.g.dreamhost.com Subject: Re: [PATCH] Add math benchmark latency test To: Arjan van de Ven , Wilco Dijkstra , "libc-alpha@sourceware.org" Cc: nd References: <0e008f2e-f41a-1bb8-803c-2f798e2c3541@gotplt.org> From: Siddhesh Poyarekar Message-ID: Date: Wed, 16 Aug 2017 14:26:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2017-08/txt/msg00658.txt.bz2 On Wednesday 16 August 2017 07:53 PM, Arjan van de Ven wrote: > well not really... > > I've been working on making expf() faster for x86 (see HJ's email > earlier), and > with a massive out of order/pipelined cpu, latency and throughput are > very distinct things. > expf() can run at a throughput of somewhere in the 10 to 11 cycles > range, while the latency > can be in the 45 to 55 cycles range. > (not trying to do benchmarking here, just wanting to show an order of > magnitude) Ah sorry, I should have been clearer - inverse in terms of units, not value, i.e. throughput is typically expressed in items/unit time while latency is expressed in time/unit item. Siddhesh