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=-3.4 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RCVD_IN_SORBS_SPAM, RP_MATCHES_RCVD shortcircuit=no autolearn=no 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 03ECD2022D for ; Sun, 26 Feb 2017 21:39:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751332AbdBZVjK (ORCPT ); Sun, 26 Feb 2017 16:39:10 -0500 Received: from mail-io0-f171.google.com ([209.85.223.171]:35041 "EHLO mail-io0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751221AbdBZVjJ (ORCPT ); Sun, 26 Feb 2017 16:39:09 -0500 Received: by mail-io0-f171.google.com with SMTP id j18so21086001ioe.2 for ; Sun, 26 Feb 2017 13:38:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=MxXS5RoZ84EBKQ4HuT/Yxcvrd9g5rypqMQBdUsTiwYE=; b=UyRhPsOtFN4JtN62X2PvOJWRmUdzluQRQxjXCoHPBChDJJY3oHPy1cNuPdx5ULmUTP FAUeSlA524MsLkZAJolQpeAdlW7DlyRpDOk9PXLpwnbn58A3853v9GlPZlLGBPWwRiO2 6A1ddZifDWmt4RNNkoMnmo/67QHKYCpYfUcwBvPiMUDGluVH5FV6qGznJrg/0dZmrhNy dZsuDA5Sf/+mlOCg+dsJosWDO0l19oFyewcofRR6X9baR2XrDTJDKafI/yiYKxx9qAPj aidJHTGleIMoSnakxJbIGUIicmRAuuGzxkpLrWnOzFsYVJz2Tqy6HWR7SJO7/RpmEhPt TnGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=MxXS5RoZ84EBKQ4HuT/Yxcvrd9g5rypqMQBdUsTiwYE=; b=ir9zr79zeVpIenm56vBMsBq8CwLkCOkuNreuw8VISrOZbCk/efmffmuv1tox/ONKhp BLWnRDadWpNcL40OvabmlcqB2EKUvU5M+Xx6i0kuTMfZFLt9kLF1VnYWs5G4cVLK8x+m 2QuKsBpVxasLTGLeeK2MzbApyyMMzIPuNzAU1ooBpXBuHbHOscIwdWfT6CNklRi86AHJ YVAAabHJUWK8LEGUH0f7OZUrXSyfCc8EOD/kznboQd+KLbx5do34KGz1lBYo13YNnFyP 4cTZgLcJB0zH0BXBtgdPLmPtW6m+Zf9HBBF8V0NmaRNB6LAl1LtY7nQ5ngI5hNBtkJHK oCZw== X-Gm-Message-State: AMke39l9yFf9So84VQy/npj0u+oS5pM96ACy3NYwE7DxNm2I9xk7UtdcmUnoD0nhm1cbEUJWimR6J4n+eT76LA== X-Received: by 10.107.57.2 with SMTP id g2mr13271954ioa.117.1488145136693; Sun, 26 Feb 2017 13:38:56 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.130.208 with HTTP; Sun, 26 Feb 2017 13:38:35 -0800 (PST) In-Reply-To: References: <22704.19873.860148.22472@chiark.greenend.org.uk> <20170226001607.GH11350@io.lakedaemon.net> <20170226173810.fp2tqikrm4nzu4uk@genre.crustytoothpaste.net> From: =?UTF-8?B?w4Z2YXIgQXJuZmrDtnLDsCBCamFybWFzb24=?= Date: Sun, 26 Feb 2017 22:38:35 +0100 Message-ID: Subject: Re: SHA1 collisions found To: Linus Torvalds Cc: "brian m. carlson" , Jason Cooper , ankostis , Junio C Hamano , Git Mailing List , Stefan Beller , David Lang , Ian Jackson , Joey Hess Content-Type: text/plain; charset=UTF-8 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Sun, Feb 26, 2017 at 8:11 PM, Linus Torvalds wrote: > But yes, SHA3-256 looks like the sane choice. Performance of hashing > is important in the sense that it shouldn't _suck_, but is largely > secondary. All my profiles on real loads (well, *my* real loads) have > shown that zlib performance is actually much more important than SHA1. What's the zlib v.s. hash ratio on those profiles? If git is switching to another hashing function given the developments in faster compression algorithms (gzip v.s. snappy v.s. zstd v.s. lz4)[1] we'll probably switch to another compression algorithm sooner than later. Would compression still be the bottleneck by far with zstd, how about with lz4? 1. https://code.facebook.com/posts/1658392934479273/smaller-and-faster-data-compression-with-zstandard/