From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23861 invoked by alias); 27 Jun 2018 15:47:31 -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 23846 invoked by uid 89); 27 Jun 2018 15:47:30 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS,URIBL_RED autolearn=ham version=3.3.2 spammy= X-HELO: relay1.mentorg.com Date: Wed, 27 Jun 2018 15:47:00 -0000 From: Joseph Myers To: Szabolcs Nagy CC: GNU C Library , Subject: Re: [PATCH 4/6] Add new log2 implementation In-Reply-To: <77536c53-496b-9b8b-88fd-f7bf4312c1c2@arm.com> Message-ID: References: <77536c53-496b-9b8b-88fd-f7bf4312c1c2@arm.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-SW-Source: 2018-06/txt/msg00852.txt.bz2 On Wed, 27 Jun 2018, Szabolcs Nagy wrote: > Improvements on Cortex-A72 compared to current glibc master: > latency: 2.0x > thruput: 1.9x Could you clarify this testing more? If you were testing on AArch64, this patch should have resulted in no changes at all to performance, because AArch64 uses sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c and you're not changing or removing the wordsize-64 version in this patch. (I expect it would make sense for this patch to remove the wordsize-64 version. Generically, it might make sense to see if the dbl-64 functions are actually any better for 32-bit systems than the dbl-64/wordsize-64 versions - if GCC is good enough at generating code for the wordsize-64 versions on 32-bit systems, reducing the number of variants by using some or all of the wordsize-64 versions also on 32-bit systems might make sense.) -- Joseph S. Myers joseph@codesourcery.com