From patchwork Mon Jun 20 12:33:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philippe Blain via GitGitGadget X-Patchwork-Id: 12887521 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFFE1C433EF for ; Mon, 20 Jun 2022 12:33:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242623AbiFTMdo (ORCPT ); Mon, 20 Jun 2022 08:33:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48244 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242711AbiFTMdW (ORCPT ); Mon, 20 Jun 2022 08:33:22 -0400 Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A920CDF89 for ; Mon, 20 Jun 2022 05:33:18 -0700 (PDT) Received: by mail-wr1-x42c.google.com with SMTP id c21so14490414wrb.1 for ; Mon, 20 Jun 2022 05:33:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:from:date:subject:fcc:content-transfer-encoding :mime-version:to:cc; bh=NnqrAMmeFWZpJ0vG9rzfZ7vph9ZQjJ6tfvtKYSViYAU=; b=RPNm8lEzqmPbdMuC6k6u+UDyH5RCekdpv7tMLuUV3YhkCClr9Gdk3G1De3dPB0AmZ+ XPjy59TWLxObhT4F3VbQ2ly92h7a8J9sn18RDpTujVbTcULKborYGaEdpHfuO+aMfwSM tt9C1cqPJn2508RwzlTgoIp+JNTg9/Q8/o61JY5NI0EPUvVb/WDgc9fPHSzZVfzNiwKl 0OjUiCHtdvmp+naMKCWuQZbk9bw42TaZfbkbk/xUAyA6nND6hrgOW38hpqIe3httFIAS hkBfRLFucyEuiffCHhLRtT3bRmello0XEN1fZl6QBc/CnKP03uFgdZ5Koak+TfxzeXUB 0+vg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:from:date:subject:fcc :content-transfer-encoding:mime-version:to:cc; bh=NnqrAMmeFWZpJ0vG9rzfZ7vph9ZQjJ6tfvtKYSViYAU=; b=ADXtjHoEx4HAxPu11krSJ9LkPbaFs1AeSczxKUTbELStjbYnnrPW2l1lBpYBPW4tuE xjUq4Aav8l6dxBzWM04U4ubAMN468rhDflG2tpWMK6ycvxHQ+XihKnst6s6b0iYlMzrF /nXaaQ+eakYwwTrQzbAk4RH2NHhWDs465McyVzsVDxQjS2Zmhuh31oRG0LgpspxxzCEh GMmq/krs24JRcOBLHCadnvnEANhYFVb0sMJYy0Dw0CDmASq91fac74r0Tkp5Xcm1p0cO axX+oimNNZ3xj/4nQk7hettxe9D386tfr1IjCBKTs1mtaQ464vtGKySsQzwBEj77jAsm IZzQ== X-Gm-Message-State: AJIora/ubWs5xxffsi+rKgcm8IchTaSV5dxDTroq5Q0+tjzZJLllp2BY QxV08IA2eeO9a2knmGlpqtlPw1ZlOa9OCA== X-Google-Smtp-Source: AGRyM1twbdwKLu3TSnXbwGvRfbVt7dX0O7M+vbHSHd/4W33KXWeIjsa3CfKnYGO3jB5Xd5iF4YNgvQ== X-Received: by 2002:a05:6000:a1e:b0:21b:8c8d:3cb5 with SMTP id co30-20020a0560000a1e00b0021b8c8d3cb5mr6827848wrb.372.1655728396641; Mon, 20 Jun 2022 05:33:16 -0700 (PDT) Received: from [127.0.0.1] ([13.74.141.28]) by smtp.gmail.com with ESMTPSA id m42-20020a05600c3b2a00b003973435c517sm15507093wms.0.2022.06.20.05.33.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jun 2022 05:33:15 -0700 (PDT) Message-Id: From: "Abhradeep Chakraborty via GitGitGadget" Date: Mon, 20 Jun 2022 12:33:08 +0000 Subject: [PATCH 0/6] [GSoC] bitmap: integrate a lookup table extension to the bitmap format Fcc: Sent MIME-Version: 1.0 To: git@vger.kernel.org Cc: Taylor Blau , Kaartic Sivaram , Abhradeep Chakraborty Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org When parsing the .bitmap file, git loads all the bitmaps one by one even if some of the bitmaps are not necessary. We can remove this overhead by loading only the necessary bitmaps. A look up table extension can solve this issue. The proposed table has: * a list of nr_entries object ids. These objects are commits that has bitmaps. Ids are stored in lexicographic order (for better searching). * a list of pairs (4-byte integers, network-byte order). The i'th pair denotes the offset and xor-offset(respectively) of the bitmap of i'th commit in the previous list. These two informations are necessary because only in this way bitmaps can be found without parsing all the bitmap. * a 4-byte integer for table specific flags (none exists currently). Whenever git want to parse the bitmap for a specific commit, it will first refer to the table and will look for the offset and xor-offset for that commit. Git will then try to parse the bitmap located at the offset position. The xor-offset can be used to find the xor-bitmap for the bitmap(if any). This process is recursive and will end if xor-offset is null (i.e. there is no xor-bitmap left). Abhradeep Chakraborty (5): Documentation/technical: describe bitmap lookup table extension pack-bitmap: prepare to read lookup table extension pack-bitmap-write.c: write lookup table extension bitmap-commit-table: add tests for the bitmap lookup table bitmap-lookup-table: add performance tests Taylor Blau (1): builtin/pack-objects.c: learn pack.writeBitmapLookupTable Documentation/config/pack.txt | 7 + Documentation/technical/bitmap-format.txt | 31 ++++ builtin/pack-objects.c | 8 + pack-bitmap-write.c | 59 +++++++- pack-bitmap.c | 172 +++++++++++++++++++++- pack-bitmap.h | 1 + t/perf/p5310-pack-bitmaps.sh | 60 +++++--- t/perf/p5326-multi-pack-bitmaps.sh | 55 ++++--- t/t5310-pack-bitmaps.sh | 14 ++ t/t5326-multi-pack-bitmaps.sh | 19 +++ 10 files changed, 375 insertions(+), 51 deletions(-) base-commit: 5699ec1b0aec51b9e9ba5a2785f65970c5a95d84 Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1266%2FAbhra303%2Fbitmap-commit-table-v1 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1266/Abhra303/bitmap-commit-table-v1 Pull-Request: https://github.com/gitgitgadget/git/pull/1266