使用profile-fast-install编译Git失败，提示缺失测试文件

问题现象 #

• 使用profile-fast-install编译Git 2.49.0、2.48.1、2.48.0版本（无论是GitHub源码仓库还是Kernel.org压缩包）时，均触发错误：

cannot open test-results/p5332-multi-pack-reuse.subtests:
    No such file or directory at ./aggregate.perl line 159.

• 直接运行性能测试脚本./p5332-multi-pack-reuse.sh时，出现如下错误：

warning: unknown preferred pack: 'pack-e837cfde5d0c6e0eebcb9aefb374b63a3726eb0f.idx'
error: no pack files to index.
error: last command exited with $?=1

核心疑问：按照官方文档编译“Profile优化版”Git是否可行？

问题复现Dockerfile #

# syntax=docker/dockerfile:1

# compile Git
# docker build -f <this file> /tmp/

# see https://github.com/git/git#
# see https://github.com/git/git/blob/master/INSTALL
# see https://www.kernel.org/pub/software/scm/git/
# see https://git-scm.com/book/en/v2/Getting-Started-Installing-Git
# see https://www.kernel.org/signature.html
# see https://marc.info/?l=git&m=156686939702976&w=2

FROM ubuntu:22.04 as base

RUN apt update -y \
    && apt install -y \
        make dh-autoreconf libcurl4-gnutls-dev libexpat1-dev zlib1g-dev libssl-dev gettext xz-utils gpg git

WORKDIR /home

# NOTE 2.49.0 was 683c54c at the time of writing
RUN git clone https://github.com/git/git.git ./git \
    && git -C ./git checkout v2.49.0

RUN cd git \
    && make configure \
    && ./configure --prefix=/home/.local \
    && make -j all \
    && make PREFIX=/home/.local profile-fast-install

# NOTE you can trigger it by
RUN cd git/t/perf \
    && rm -rf test-results \
    && ./run p5332-multi-pack-reuse.sh

测试执行日志 #

root@0a1a0100a22b:/git/t/perf# rm -rf test-results/
root@0a1a0100a22b:/git/t/perf# ./p5332-multi-pack-reuse.sh -xv
checking prerequisite: SYMLINKS

mkdir -p "$TRASH_DIRECTORY/prereq-test-dir-SYMLINKS" &&
(
    cd "$TRASH_DIRECTORY/prereq-test-dir-SYMLINKS" &&
    # test whether the filesystem supports symbolic links
    ln -s x y && test -h y

)
+ mkdir -p /git/t/perf/trash directory.p5332-multi-pack-reuse/prereq-test-dir-SYMLINKS
+ cd /git/t/perf/trash directory.p5332-multi-pack-reuse/prereq-test-dir-SYMLINKS
+ ln -s x y
+ test -h y
prerequisite SYMLINKS ok
expecting success of p5332.1 'create 1-pack scenario':
        repack_into_n_chunks $nr_packs
    
+ repack_into_n_chunks 1
+ git repack -adk
Enumerating objects: 774560, done.
Counting objects: 100% (387280/387280), done.
Delta compression using up to 8 threads
Compressing objects: 100% (92515/92515), done.
Writing objects: 100% (387280/387280), done.
Total 387280 (delta 292211), reused 387280 (delta 292211), pack-reused 0 (from 0)
+ test 1 -eq 1
+ return
ok 1 - create 1-pack scenario

expecting success of p5332.2 'setup bitmaps for 1-pack scenario':
        find $packdir -type f -name "*.idx" | sed -e "s/.*\/\(.*\)$/\+\1/g" |
        git multi-pack-index write --stdin-packs --bitmap \
            --preferred-pack="$(find_pack $(git rev-parse HEAD))"
    
+ find .git/objects/pack -type f -name *.idx
+ sed -e s/.*\/\(.*\)$/\+\1/g
+ git rev-parse HEAD
+ find_pack 683c54c999c301c2cd6f715c411407c413b1d84e
+ git show-index
+ grep -q 683c54c999c301c2cd6f715c411407c413b1d84e
+ basename .git/objects/pack/pack-e837cfde5d0c6e0eebcb9aefb374b63a3726eb0f.idx
+ git multi-pack-index write --stdin-packs --bitmap --preferred-pack=pack-e837cfde5d0c6e0eebcb9aefb374b63a3726eb0f.idx
warning: unknown preferred pack: 'pack-e837cfde5d0c6e0eebcb9aefb374b63a3726eb0f.idx'
error: no pack files to index.
error: last command exited with $?=1
not ok 2 - setup bitmaps for 1-pack scenario
#   
#           find $packdir -type f -name "*.idx" | sed -e "s/.*\/\(.*\)$/\+\1/g" |
#           git multi-pack-index write --stdin-packs --bitmap \
#               --preferred-pack="$(find_pack $(git rev-parse HEAD))"
#       
1..2

解决方案与可行性说明 #

编译Profile优化版Git是完全可行的，当前错误是性能测试脚本p5332-multi-pack-reuse.sh的逻辑问题，与profile-fast-install本身无关。

问题根源 #

测试脚本中，sed -e "s/.*\/\(.*\)$/\+\1/g"会给每个pack文件名前添加+号，但--preferred-pack参数传入的是不带+号的pack文件名，导致Git无法识别该pack，进而触发错误。

修复步骤 #

1. 修改测试脚本p5332-multi-pack-reuse.sh，在生成--preferred-pack参数时，给pack文件名前添加+号：
   将原代码：

   git multi-pack-index write --stdin-packs --bitmap \
       --preferred-pack="$(find_pack $(git rev-parse HEAD))"
   

   修改为：

   git multi-pack-index write --stdin-packs --bitmap \
       --preferred-pack="+$(find_pack $(git rev-parse HEAD))"
   

2. 重新运行测试脚本，或直接跳过该测试继续完成编译（若仅需编译优化版Git，无需通过全部性能测试）。

替代编译方式 #

若不想修改测试脚本，可跳过性能测试环节，直接手动执行Profile优化流程：

1. 先完成普通编译：make -j all
2. 生成Profile数据：make profile（运行性能测试生成Profile文件）
3. 编译优化版：make profile-fast
4. 安装：make PREFIX=/home/.local install

内容的提问来源于stack exchange，提问作者Michael Teresi