From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.3 required=3.0 tests=AWL,BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 396E02027B for ; Thu, 2 Mar 2017 14:40:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754082AbdCBOkI (ORCPT ); Thu, 2 Mar 2017 09:40:08 -0500 Received: from mout.gmx.net ([212.227.17.21]:55326 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752940AbdCBOjq (ORCPT ); Thu, 2 Mar 2017 09:39:46 -0500 Received: from virtualbox ([37.201.192.48]) by mail.gmx.com (mrgmx101 [212.227.17.168]) with ESMTPSA (Nemesis) id 0MhMg2-1cxHY81F8k-00Mdh1; Thu, 02 Mar 2017 15:39:30 +0100 Date: Thu, 2 Mar 2017 15:39:27 +0100 (CET) From: Johannes Schindelin X-X-Sender: virtualbox@virtualbox To: Jeff King cc: Linus Torvalds , Junio C Hamano , Marc Stevens , Dan Shumow , Git Mailing List Subject: Re: [PATCH] Put sha1dc on a diet In-Reply-To: <20170301231921.2puf7o7jkrujscwn@sigill.intra.peff.net> Message-ID: References: <20170301231921.2puf7o7jkrujscwn@sigill.intra.peff.net> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Provags-ID: V03:K0:VcbkxHhfixPKt2FdyVhm9OclLKzDD5+0TNCxvV3JvbUuMWklGAt surIYTXPlxI7S6kf4ttL1tCcksfmxegSJGqZayUgm1LmKU9O/wYWZnGlGXDerdw/t7cOf7u a8Q41m7VSJ20C+xqJQ2Hqwr5+oR4vLKbC7gX9bApe6PwAmSVrep6i45JKHzzH88iWhekmOE zbIBBKeQjEA9HwklcNCgA== X-UI-Out-Filterresults: notjunk:1;V01:K0:HuOffjyF3gM=:w4tubxcbcnWQd8BZNtAPJ9 4BOLY1Zqezs/6dGi6ZQygdxFlQNqeVJSdzuC0uKmP7jogl4qrkPoV88k6744c9P6zUKvdhVyl S9WiiM6xcNjaF0LMsK+QwlFfowqABcCm0ablJFw3FuXvZUdU2DkE+8GGG/LbiMPnlmM9DKlGv NNcN9RcWgbxXNMKw0f7aZfAjyK1jt1S28sQ+9C7gHTXNqoMyNobVl/PygYO6M0NNOtVQ3FBqd SoIRDiKUqd0Bzi0tA0Bni9dOp6XxnLCMK3j/i+APWmq6jgFks02dJYh2sTT6zWHpkXiUwU/gI atz5MdX/uiUI+xWRYEfwWiumQEfooAfbUUuBzx8Pzei/FJsUR0pqR5W9aAvJOOmf57sX0yn6X WOewG6VnM7ZXFj3ztIQ9XxtCHMzOZ0ZnBrb9j5u8t19omHDBuMWD1va3+7pFYEnUi8LZq/VLy LE3Eu/nO44SujrLdAnAVMGHFVxZ1jYGDHVvPLVviib0eIjvUqGpgxwZuWVvwOqnp5fXjEXoMP FEHM6OpNOXOkSpb9NBuC+Zq8k6K8lKzXmy3DvfnSfeV0t2n/WWG1CjoYQB5WIYDSiBwoZV2Ie DQiTlnih0YjiMEL4qe4fKV2id+fvi/H3o628UFhHQ27rI4SxT1Sx8XEPW1w5MHycgG43NLhFv 6uUzNcjqoVlhsx//3duOLWaevHxr6l3QNe1DfShC4tNAWyNAhL5sY/bPRk6T3uyc6W7Lli7Ly UUq8Ojua5Xj7pjRWV71DKl4V60RaGlSrFc1OVKshFKO+/0+qa2XSt4KIISc+4w60tz6coLvDu IxQRcmzqTXh80QjPu3pAtFjSCjIrQ== Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Hi Peff, On Wed, 1 Mar 2017, Jeff King wrote: > I do think that could argue for turning on the collision detection only > during object-write operations, which is where it matters. It would be > really trivial to flip the "check collisions" bit on sha1dc. But I > suspect you could go faster still by compiling against two separate > implementations: the fast-as-possible one (which could be openssl or > blk-sha1), and the slower-but-careful sha1dc. Given the speed difference between OpenSSL and sha1dc, it would be a wise thing indeed to do sha1dc only where objects enter from possibly untrusted sources, and use OpenSSL for all other hashing. Ciao, Johannes