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, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID 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 39B1020958 for ; Thu, 23 Mar 2017 17:16:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755530AbdCWRQ0 (ORCPT ); Thu, 23 Mar 2017 13:16:26 -0400 Received: from mail-io0-f179.google.com ([209.85.223.179]:36065 "EHLO mail-io0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750952AbdCWRQZ (ORCPT ); Thu, 23 Mar 2017 13:16:25 -0400 Received: by mail-io0-f179.google.com with SMTP id l7so1462759ioe.3 for ; Thu, 23 Mar 2017 10:16:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=C+OuyAfheZjA0XfoRbYxpc5dlhT5ojMOEKMuwylcqHc=; b=CksZRQiyn+Gy2T62jr3shVcpSEABJPsxwPiKypYp0CybadPRQa834N+woihlPPPnmb 0umNXLcaIyzAYMnYQGLlYV7qMGGAylFZIolvU+L0XdsyBUZavRqzl/4TonbnPnq+EhKX xXqYmovTmTD8A2mjAkmz2aXd7oqBNeOKTv5eZLP0ThBmoakVnYK6s/X7v8VYPnzruQFT cFK5PBXFH2aNWS0TsHg6gvKUTMscJ8svd/+/TwSbHmoGhJCp5l4dLrdJMX76bauEFMqN bjuP2lUUMIPA2CFmJhJXMyHzevfy95MgcE3FN4tu1FBNAfcRxfxJ1pDah3RjqySKDVHU QcsQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=C+OuyAfheZjA0XfoRbYxpc5dlhT5ojMOEKMuwylcqHc=; b=dbRKLdC8Bh4XUv1RB3lpYilaHu2JS2Qrn6keajcEUD9zux+yxFpyDToFE5lm2jbY74 BhQWQh4rVTr6LxYrjL7xMeyaF743N9O2GONJWCze85BdiCIqZYGQqXAA4jGKTN/GujU3 NU7oEHTnIiCqiiYFjMpK7Da18dVyKUEO3pBcJu7EWUhGZ5WYqjwtbgTedrhb/Lu9P4ON 8RhDMbgtyuWF5dzI4u0TWHxlgXZ6Ey7NF8dh34kRRdwjn/GUUiMysO9/FibuahPufrO8 kfo807/YUD/NavkXJKCgoI7GS3Lrt4/jOVsk2R5gDm7gx8lg+UquPecyAexa/Nb5R4u3 GDSA== X-Gm-Message-State: AFeK/H23q098gR28Lwe65qk1nEzeNDG4HKRDEfa0izZvFmALXbuphN3h3AdjiG/Kwp6Iwxyn5TovYLrW5oZvgA== X-Received: by 10.107.136.93 with SMTP id k90mr3713285iod.224.1490289384560; Thu, 23 Mar 2017 10:16:24 -0700 (PDT) MIME-Version: 1.0 Received: by 10.107.136.102 with HTTP; Thu, 23 Mar 2017 10:16:23 -0700 (PDT) In-Reply-To: References: <2B1DE627-11C8-4FA5-A354-76B6C475666A@gmail.com> <20170322220246.GD26108@aiede.mtv.corp.google.com> From: Linus Torvalds Date: Thu, 23 Mar 2017 10:16:23 -0700 X-Google-Sender-Auth: cKMQbAizyk7Z6YLhyvvCywWvtCo Message-ID: Subject: Re: USE_SHA1DC is broken in pu To: Johannes Schindelin Cc: Jonathan Nieder , Junio C Hamano , Lars Schneider , Jeff King , Git Mailing List 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 Thu, Mar 23, 2017 at 9:43 AM, Johannes Schindelin wrote: > > What I am saying is that this should be a more fine-grained, runtime knob. No it really shouldn't. > If I write out an index, I should not suffer the slowdown from detecting > collisions. The index case is a complete red herring. As already noted, the proper fix for the index case is to simply do it asynchronously on read. On write, it's harder to do asynchronously, but for a 300MB index file you're likely going to be doing IO in the middle, so it's probably not even noticeable. But even *if* you want to worry about the index file, it shouldn't be a runtime knob. The index file is completely different from the other uses of SHA1DC. But the fact is, if you don't want SHA1DC, and you have crazy special cases, you just continue to build with openssl support instead. Nobody else should ever have to worry about *your* crazy cases. Linus