From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.4 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 14694 invoked from network); 15 Aug 2021 16:41:46 -0000 Received: from mother.openwall.net (195.42.179.200) by inbox.vuxu.org with ESMTPUTF8; 15 Aug 2021 16:41:46 -0000 Received: (qmail 15976 invoked by uid 550); 15 Aug 2021 16:41:44 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 15958 invoked from network); 15 Aug 2021 16:41:44 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nexgo.de; s=vfde-smtpout-mb-15sep; t=1629045574; bh=mwX+17UtIH8VnyGnEHTYDogxTg8eAGfZ2RzXGCpPdeM=; h=From:To:Cc:References:In-Reply-To:Subject:Date; b=Puo2olZq95uHRhjAYuaX+uZrGzYZsk/b0pgFORnpn6iJag4b778/PPo3dBhcssEFK EV7wWLCHo/uF+c2S2UzmNIqjj5wBXIVvxmJ2hXUbpsZ0AIvJSJpJGDy5TkNKwfRWff FwATfjwQwkkjPeRMuOAnaSnH+t6bXjoNmdblui6s= Message-ID: From: "Stefan Kanthak" To: "Rich Felker" Cc: "Szabolcs Nagy" , References: <0C6AAAD55DA44C6189B2FF4F5FB2C3E7@H270> <20210810213455.GB37904@port70.net> <20210814234612.GH37904@port70.net> <367A4018B58A4E308E2A95404362CBFB@H270> <20210815145614.GI37904@port70.net> <1F3569BD7D6E45889B7518DC9BE5004B@H270> <20210815154843.GH13220@brightrain.aerifal.cx> In-Reply-To: <20210815154843.GH13220@brightrain.aerifal.cx> Date: Sun, 15 Aug 2021 18:29:08 +0200 Organization: Me, myself & IT MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.1.7601.24158 X-purgate-type: clean X-purgate-Ad: Categorized by eleven eXpurgate (R) http://www.eleven.de X-purgate: This mail is considered clean (visit http://www.eleven.de for further information) X-purgate: clean X-purgate-size: 1301 X-purgate-ID: 155817::1629045574-00000B26-5315023E/0/0 Subject: Re: [musl] [PATCH #2] Properly simplified nextafter() Rich Felker wrote: > On Sun, Aug 15, 2021 at 05:19:05PM +0200, Stefan Kanthak wrote: >> Szabolcs Nagy wrote: >> >> > * Stefan Kanthak [2021-08-15 09:04:55 +0200]: >> >> Szabolcs Nagy wrote: >> >>> you should benchmark, but the second best is to look >> >>> at the longest dependency chain in the hot path and >> >>> add up the instruction latencies. >> >> >> >> 1 billion calls to nextafter(), with random from, and to either 0 or +INF: >> >> run 1 against glibc, 8.58 ns/call >> >> run 2 against musl original, 3.59 >> >> run 3 against musl patched, 0.52 >> >> run 4 the pure floating-point variant from 0.72 >> >> my initial post in this thread, >> >> run 5 the assembly variant I posted. 0.28 ns/call >> > >> > thanks for the numbers. it's not the best measurment >> >> IF YOU DON'T LIKE IT, PERFORM YOUR OWN MEASUREMENT! > > The burden of performing a meaningful measurement is on the party who > says there's something that needs to be changed. I offered you two patches which speed a rather simple function by a measured factor of 5 and 7 respectively. IF YOU DOUBT THESE NUMBERS, PROVIDE YOUR OWN! Stefan