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This puts delta resolving on each base on a separate thread, one base cache per thread. Per-thread data is grouped in struct thread_local. When running with nr_threads == 1, no pthreads calls are made. The system essentially runs in non-thread mode. An experiment on a Xeon 24 core machine with git.git shows that performance does not increase proportional to the number of cores. So by default, we use maximum 3 cores. Some numbers with --threads from 1 to 16: 1..4 real 0m8.003s 0m5.307s 0m4.321s 0m3.830s user 0m7.720s 0m8.009s 0m8.133s 0m8.305s sys 0m0.224s 0m0.372s 0m0.360s 0m0.360s 5..8 real 0m3.727s 0m3.604s 0m3.332s 0m3.369s user 0m9.361s 0m9.817s 0m9.525s 0m9.769s sys 0m0.584s 0m0.624s 0m0.540s 0m0.560s 9..12 real 0m3.036s 0m3.139s 0m3.177s 0m2.961s user 0m8.977s 0m10.205s 0m9.737s 0m10.073s sys 0m0.596s 0m0.680s 0m0.684s 0m0.680s 13..16 real 0m2.985s 0m2.894s 0m2.975s 0m2.971s user 0m9.825s 0m10.573s 0m10.833s 0m11.361s sys 0m0.788s 0m0.732s 0m0.904s 0m1.016s On an Intel dual core and linux-2.6.git 1..4 real 2m37.789s 2m7.963s 2m0.920s 1m58.213s user 2m28.415s 2m52.325s 2m50.176s 2m41.187s sys 0m7.808s 0m11.181s 0m11.224s 0m10.731s Thanks Ramsay Jones for troubleshooting and support on MinGW platform. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
100 lines
3.3 KiB
Text
100 lines
3.3 KiB
Text
git-index-pack(1)
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=================
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NAME
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----
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git-index-pack - Build pack index file for an existing packed archive
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SYNOPSIS
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--------
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[verse]
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'git index-pack' [-v] [-o <index-file>] <pack-file>
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'git index-pack' --stdin [--fix-thin] [--keep] [-v] [-o <index-file>]
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[<pack-file>]
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DESCRIPTION
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-----------
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Reads a packed archive (.pack) from the specified file, and
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builds a pack index file (.idx) for it. The packed archive
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together with the pack index can then be placed in the
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objects/pack/ directory of a git repository.
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OPTIONS
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-------
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-v::
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Be verbose about what is going on, including progress status.
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-o <index-file>::
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Write the generated pack index into the specified
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file. Without this option the name of pack index
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file is constructed from the name of packed archive
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file by replacing .pack with .idx (and the program
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fails if the name of packed archive does not end
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with .pack).
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--stdin::
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When this flag is provided, the pack is read from stdin
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instead and a copy is then written to <pack-file>. If
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<pack-file> is not specified, the pack is written to
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objects/pack/ directory of the current git repository with
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a default name determined from the pack content. If
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<pack-file> is not specified consider using --keep to
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prevent a race condition between this process and
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'git repack'.
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--fix-thin::
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Fix a "thin" pack produced by `git pack-objects --thin` (see
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linkgit:git-pack-objects[1] for details) by adding the
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excluded objects the deltified objects are based on to the
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pack. This option only makes sense in conjunction with --stdin.
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--keep::
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Before moving the index into its final destination
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create an empty .keep file for the associated pack file.
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This option is usually necessary with --stdin to prevent a
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simultaneous 'git repack' process from deleting
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the newly constructed pack and index before refs can be
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updated to use objects contained in the pack.
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--keep=<msg>::
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Like --keep create a .keep file before moving the index into
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its final destination, but rather than creating an empty file
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place '<msg>' followed by an LF into the .keep file. The '<msg>'
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message can later be searched for within all .keep files to
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locate any which have outlived their usefulness.
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--index-version=<version>[,<offset>]::
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This is intended to be used by the test suite only. It allows
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to force the version for the generated pack index, and to force
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64-bit index entries on objects located above the given offset.
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--strict::
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Die, if the pack contains broken objects or links.
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--threads=<n>::
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Specifies the number of threads to spawn when resolving
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deltas. This requires that index-pack be compiled with
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pthreads otherwise this option is ignored with a warning.
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This is meant to reduce packing time on multiprocessor
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machines. The required amount of memory for the delta search
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window is however multiplied by the number of threads.
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Specifying 0 will cause git to auto-detect the number of CPU's
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and use maximum 3 threads.
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Note
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----
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Once the index has been created, the list of object names is sorted
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and the SHA1 hash of that list is printed to stdout. If --stdin was
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also used then this is prefixed by either "pack\t", or "keep\t" if a
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new .keep file was successfully created. This is useful to remove a
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.keep file used as a lock to prevent the race with 'git repack'
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mentioned above.
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GIT
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---
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Part of the linkgit:git[1] suite
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