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, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,T_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 C810E1F404 for ; Fri, 30 Mar 2018 21:27:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752846AbeC3V07 (ORCPT ); Fri, 30 Mar 2018 17:26:59 -0400 Received: from cloud.peff.net ([104.130.231.41]:49508 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752571AbeC3V06 (ORCPT ); Fri, 30 Mar 2018 17:26:58 -0400 Received: (qmail 918 invoked by uid 109); 30 Mar 2018 21:26:58 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Fri, 30 Mar 2018 21:26:58 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 633 invoked by uid 111); 30 Mar 2018 21:27:57 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with (ECDHE-RSA-AES256-GCM-SHA384 encrypted) SMTP; Fri, 30 Mar 2018 17:27:57 -0400 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Fri, 30 Mar 2018 17:26:56 -0400 Date: Fri, 30 Mar 2018 17:26:56 -0400 From: Jeff King To: =?utf-8?B?Tmd1eeG7hW4gVGjDoWkgTmfhu41j?= Duy Cc: avarab@gmail.com, e@80x24.org, git@vger.kernel.org, gitster@pobox.com Subject: Re: [PATCH v7 13/13] pack-objects: reorder members to shrink struct object_entry Message-ID: <20180330212656.GK14782@sigill.intra.peff.net> References: <20180318142526.9378-1-pclouds@gmail.com> <20180324063353.24722-1-pclouds@gmail.com> <20180324063353.24722-14-pclouds@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180324063353.24722-14-pclouds@gmail.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Sat, Mar 24, 2018 at 07:33:53AM +0100, Nguyễn Thái Ngọc Duy wrote: > Previous patches leave lots of holes and padding in this struct. This > patch reorders the members and shrinks the struct down to 80 bytes > (from 136 bytes, before any field shrinking is done) with 16 bits to > spare (and a couple more in in_pack_header_size when we really run out > of bits). Out of curiosity, did you count this yourself, or did you double-check with a few compilers to make sure they all produce the same result? So having read the whole thing now, I think most of my original concerns have been addressed. I do think readability takes a hit, but it's not _too_ bad. There are a few things that have become more brittle, but I can't think of anything on the horizon that would bite us. -Peff