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 2AF151F404 for ; Fri, 30 Mar 2018 21:24:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752774AbeC3VYX (ORCPT ); Fri, 30 Mar 2018 17:24:23 -0400 Received: from cloud.peff.net ([104.130.231.41]:49486 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752571AbeC3VYW (ORCPT ); Fri, 30 Mar 2018 17:24:22 -0400 Received: (qmail 750 invoked by uid 109); 30 Mar 2018 21:24:22 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Fri, 30 Mar 2018 21:24:22 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 613 invoked by uid 111); 30 Mar 2018 21:25:21 -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 17:25:21 -0400 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Fri, 30 Mar 2018 17:24:20 -0400 Date: Fri, 30 Mar 2018 17:24:20 -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 12/13] pack-objects: shrink delta_size field in struct object_entry Message-ID: <20180330212419.GJ14782@sigill.intra.peff.net> References: <20180318142526.9378-1-pclouds@gmail.com> <20180324063353.24722-1-pclouds@gmail.com> <20180324063353.24722-13-pclouds@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180324063353.24722-13-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 07:33:52AM +0100, Nguyễn Thái Ngọc Duy wrote: > Allowing a delta size of 64 bits is crazy. Shrink this field down to > 31 bits with one overflow bit. > > If we find an existing delta larger than 2GB, we do not cache > delta_size at all and will get the value from oe_size(), potentially > from disk if it's larger than 4GB. Since we have a fallback, we can put this slider wherever we want. Probably something like 20 bits would be plenty, if we ever needed to squeeze in a few more small-bit items. > @@ -2004,10 +2006,12 @@ static int try_delta(struct unpacked *trg, struct unpacked *src, > delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size); > if (!delta_buf) > return 0; > + if (delta_size >= (1 << OE_DELTA_SIZE_BITS)) > + return 0; This is the other spot that needs to be "1U". How come this doesn't get a pdata->oe_delta_size_limit like we have pdata->oe_size_limit? Would we want a matching $GIT_TEST_OE_DELTA_SIZE_BITS to test it, too? -Peff