From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754314Ab2IWRaa (ORCPT ); Sun, 23 Sep 2012 13:30:30 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:58675 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754103Ab2IWRa3 (ORCPT ); Sun, 23 Sep 2012 13:30:29 -0400 From: Michal Nazarewicz To: George Spelvin , vda.linux@googlemail.com Cc: hughd@google.com, linux-kernel@vger.kernel.org, linux@horizon.com Subject: Re: [PATCH 2/4] lib: vsprintf: Optimize division by 10000 In-Reply-To: <1343971271-13355-2-git-send-email-linux@horizon.com> Organization: Google Inc References: <1343971271-13355-1-git-send-email-linux@horizon.com> <1343971271-13355-2-git-send-email-linux@horizon.com> User-Agent: Notmuch/0.14+22~g8bdc16b (http://notmuchmail.org) Emacs/24.2.50.1 (x86_64-unknown-linux-gnu) X-Face: PbkBB1w#)bOqd`iCe"Ds{e+!C7`pkC9a|f)Qo^BMQvy\q5x3?vDQJeN(DS?|-^$uMti[3D*#^_Ts"pU$jBQLq~Ud6iNwAw_r_o_4]|JO?]}P_}Nc&"p#D(ZgUb4uCNPe7~a[DbPG0T~!&c.y$Ur,=N4RT>]dNpd;KFrfMCylc}gc??'U2j,!8%xdD Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwBAMAAAClLOS0AAAAJFBMVEWbfGlUPDDHgE57V0jUupKjgIObY0PLrom9mH4dFRK4gmjPs41MxjOgAAACQElEQVQ4jW3TMWvbQBQHcBk1xE6WyALX1069oZBMlq+ouUwpEQQ6uRjttkWP4CmBgGM0BQLBdPFZYPsyFUo6uEtKDQ7oy/U96XR2Ux8ehH/89Z6enqxBcS7Lg81jmSuujrfCZcLI/TYYvbGj+jbgFpHJ/bqQAUISj8iLyu4LuFHJTosxsucO4jSDNE0Hq3hwK/ceQ5sx97b8LcUDsILfk+ovHkOIsMbBfg43VuQ5Ln9YAGCkUdKJoXR9EclFBhixy3EGVz1K6eEkhxCAkeMMnqoAhAKwhoUJkDrCqvbecaYINlFKSRS1i12VKH1XpUd4qxL876EkMcDvHj3s5RBajHHMlA5iK32e0C7VgG0RlzFPvoYHZLRmAC0BmNcBruhkE0KsMsbEc62ZwUJDxWUdMsMhVqovoT96i/DnX/ASvz/6hbCabELLk/6FF/8PNpPCGqcZTGFcBhhAaZZDbQPaAB3+KrWWy2XgbYDNIinkdWAFcCpraDE/knwe5DBqGmgzESl1p2E4MWAz0VUPgYYzmfWb9yS4vCvgsxJriNTHoIBz5YteBvg+VGISQWUqhMiByPIPpygeDBE6elD973xWwKkEiHZAHKjhuPsFnBuArrzxtakRcISv+XMIPl4aGBUJm8Emk7qBYU8IlgNEIpiJhk/No24jHwkKTFHDWfPniR4iw5vJaw2nzSjfq2zffcE/GDjRC2dn0J0XwPAbDL84TvaFCJEU4Oml9pRyEUhR3Cl2t01AoEjRbs0sYugp14/4X5n4pU4EHHnMAAAAAElFTkSuQmCC X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 Date: Sun, 23 Sep 2012 19:30:20 +0200 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Fri, Aug 03 2012, George Spelvin wrote: > The same multiply-by-inverse technique can be used to > convert division by 10000 to a 32x32->64-bit multiply. > > Signed-off-by: George Spelvin You are using a 64-bit multiply in a path that is designed for 32-bit processors, which makes me feel that it will be slower. --=20 Best regards, _ _ .o. | Liege of Serenely Enlightened Majesty of o' \,=3D./ `o ..o | Computer Science, Micha=C5=82 =E2=80=9Cmina86=E2=80=9D Nazarewicz = (o o) ooo +------------------ooO--(_)--Ooo-- --=-=-= Content-Type: multipart/signed; boundary="==-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" --==-=-= Content-Type: text/plain --==-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iQIcBAEBAgAGBQJQX0csAAoJECBgQBJQdR/0OeEP/2Sf8+wGJcaYa/KotLFECZ/0 ST0d5SkTtm/SyC1KAxMRWZXhbpIFU4zmiyrLp/8aw/8GVlabUKHbuoemoOzkGNEo FMTPz1d4jD4xZFyp2534R10NYDPLk4NRKy9dyrEOnx4pSa5KHMTRqzlt6DYfTVdz myrvYMAt1HbkP70HzjHQIkbKGj1XRE2NF/vWGCoyHhcCaJlUZW5YYzYkurcE9Tyd fs6RZv/FSxWmSCykVXTlzCo8TaKNiJyDfIJ6KW2jg54hGFAo7jDS77PxU8/deWvD zMCLbNa1rXcl9OcVKymEHxtcR8nTTjtZ/tXIQm7sntOgfIsfOX1R6shA1K75GNmd mBYa+X5MsAwbaMHNpVo71xAeG68yOTYo6wgDtdd+hEhl/GU0WXTFd49NazE2ety9 CrveN4sbo+YPJoPUF8KOsw+peTwLm6ZBDWuZSNWTvlQF/8SPqESjHkX0rm6gTNrq 28UJgCGmjLlES/NJEcxwN40IfwhuU+Jvnb6F4D5FNZDOsmz09RD1GAeh3AP9CABj FTxq+6/kWIkraA92GZ7J75yqay1AzwQft8miPabcYHwRZuqiRg69kCD7VPso7KLW JJNNT8QoM00TzKOIpIZ9mcpM0w8BtEBe7SbAl3MICuOPuTmll8b/kV8+UZi8VJpx pJieVGUoN9U9bKqJjwdC =QZya -----END PGP SIGNATURE----- --==-=-=-- --=-=-=--