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=-4.9 required=3.0 tests=AWL,BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 23174203E1 for ; Wed, 27 Jul 2016 16:50:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757222AbcG0Quu (ORCPT ); Wed, 27 Jul 2016 12:50:50 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:33446 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757213AbcG0Qut convert rfc822-to-8bit (ORCPT ); Wed, 27 Jul 2016 12:50:49 -0400 Received: by mail-wm0-f68.google.com with SMTP id o80so7338704wme.0 for ; Wed, 27 Jul 2016 09:50:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=3OnC5ip7dA5xwdC15NscE/eRGdq1+NuD0fj8N7BAHnk=; b=yHi1NI0MP3THaAWySI88hM5UFI9Nrk8mqS/rhQcoFcenNhYBR/dkwzTwnlZ8RXLwrA WiTBp7VlIDeIZQYM76x6eSYmzZk2XLxIA/tcMyp0ZrtWeLFxfooR0tDllrjhzNidHcWB 1KCnQrQUUTk02/MSmJroM557/QKK7DR1vgpvZJMZxl8VVG/FK6fX2m19bLosUeGAPeJV RSx9bkQ6xaZ6eLcwGzMOfQyFHSnUZgo62i70XKyl5PBk0p+jcb0l6Xx/cfDI4LeiOjNI jCS3XmOqoAHwdr5dWTVZRmzusaIsCvzYsRq5OWta63eiwXqUeFdNzxaF9c5GV+XqfqKx vKrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=3OnC5ip7dA5xwdC15NscE/eRGdq1+NuD0fj8N7BAHnk=; b=ILYPMvVnnRSsX1Jd+ddfxIZna2QJlLkcMhep3cxVXvbnQFXL5BYmDT+jvdrPc16GO3 IsxYFpQZ8DPK/oeuTOBt6yxI99/llnOJZ+t2qLSK4m9B8h3YnT6NgkS7k8ytFmKzbGxt /jSv2h+IrZBpnJErZtIF4q4jXDHmdQ7Myppst08lXAxgsBsWPMUoWGKgqpvOQTlMniaN dZ4JqGqG8B/trF7e8/LEMyigvX72op7FCRb1Skj+WRLa/06AMStbt2Z10dMPyAUgC/Jb FiMvSArhlKTEI/Oz6ZuJz6v8ANI8i9PrV884MhsFJNgPmQbMaMft1gMOZRK3+F1iEf5n czXw== X-Gm-Message-State: AEkoous7fCnaKQIHjKg7fT9jhUbWHn7pc4xe7hTiPtzeLjxwF7Ycpeb21Agi60dLYE0Q8g== X-Received: by 10.194.164.229 with SMTP id yt5mr28587927wjb.39.1469638242935; Wed, 27 Jul 2016 09:50:42 -0700 (PDT) Received: from slxbook4.ads.autodesk.com ([62.159.156.210]) by smtp.gmail.com with ESMTPSA id f4sm39245324wmf.8.2016.07.27.09.50.41 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 27 Jul 2016 09:50:42 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [PATCH v2 4/5] convert: generate large test files only once From: Lars Schneider In-Reply-To: <20160727133214.GA14928@sigill.intra.peff.net> Date: Wed, 27 Jul 2016 18:50:40 +0200 Cc: =?utf-8?Q?Torsten_B=C3=B6gershausen?= , Git Mailing List , Junio C Hamano , =?utf-8?Q?Jakub_Nar=C4=99bski?= , mlbright@gmail.com, remi.galan-alfonso@ensimag.grenoble-inp.fr, pclouds@gmail.com, e@80x24.org, ramsay@ramsayjones.plus.com Content-Transfer-Encoding: 8BIT Message-Id: <1D133FC4-032F-434A-882C-5931AA285CD9@gmail.com> References: <20160722154900.19477-1-larsxschneider@gmail.com> <20160727000605.49982-1-larsxschneider@gmail.com> <20160727000605.49982-5-larsxschneider@gmail.com> <20160727133214.GA14928@sigill.intra.peff.net> To: Jeff King X-Mailer: Apple Mail (2.3124) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org > On 27 Jul 2016, at 15:32, Jeff King wrote: > > On Wed, Jul 27, 2016 at 04:35:32AM +0200, Torsten Bögershausen wrote: > >>> + mkdir -p generated-test-data && >>> + for i in $(test_seq 1 $T0021_LARGE_FILE_SIZE) >>> + do >>> + # Generate 1MB of empty data and 100 bytes of random characters >>> + printf "%1048576d" 1 >>> + printf "$(LC_ALL=C tr -dc "A-Za-z0-9" >8)) count=1 2>/dev/null)" >> I'm not sure how portable /dev/urandom is. >> The other thing, that "really random" numbers are an overkill, and >> it may be easier to use pre-defined numbers, > > Right, there are a few reasons not to use /dev/urandom: > > - it's not portable > > - if we have to generate a lot of numbers, it drains the system's > entropy pool, which is an unfriendly thing to do (and may also be > slow) > > - it makes our tests random! This sounds like a good thing, but it > means that if some input happens to cause failure, you are unlikely > to be able to reproduce it. > > Instead, use test-genrandom, which is an LCG that starts at a seed. So > you get a large amount of random-ish quickly and portably, and you get > the same data each time. Thank you! That's exactly what I need here :-) - Lars