git/Documentation/config/pack.txt

pack.window::
	The size of the window used by linkgit:git-pack-objects[1] when no
	window size is given on the command line. Defaults to 10.

pack.depth::
	The maximum delta depth used by linkgit:git-pack-objects[1] when no
	maximum depth is given on the command line. Defaults to 50.
	Maximum value is 4095.

pack.windowMemory::
	The maximum size of memory that is consumed by each thread
	in linkgit:git-pack-objects[1] for pack window memory when
	no limit is given on the command line.  The value can be
	suffixed with "k", "m", or "g".  When left unconfigured (or
	set explicitly to 0), there will be no limit.

pack.compression::
	An integer -1..9, indicating the compression level for objects
	in a pack file. -1 is the zlib default. 0 means no
	compression, and 1..9 are various speed/size tradeoffs, 9 being
	slowest.  If not set,  defaults to core.compression.  If that is
	not set,  defaults to -1, the zlib default, which is "a default
	compromise between speed and compression (currently equivalent
	to level 6)."
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Note that changing the compression level will not automatically recompress
all existing objects. You can force recompression by passing the -F option
to linkgit:git-repack[1].

pack.allowPackReuse::
	When true, and when reachability bitmaps are enabled,
	pack-objects will try to send parts of the bitmapped packfile
	verbatim. This can reduce memory and CPU usage to serve fetches,
	but might result in sending a slightly larger pack. Defaults to
	true.

pack.island::
	An extended regular expression configuring a set of delta
	islands. See "DELTA ISLANDS" in linkgit:git-pack-objects[1]
	for details.

pack.islandCore::
	Specify an island name which gets to have its objects be
	packed first. This creates a kind of pseudo-pack at the front
	of one pack, so that the objects from the specified island are
	hopefully faster to copy into any pack that should be served
	to a user requesting these objects. In practice this means
	that the island specified should likely correspond to what is
	the most commonly cloned in the repo. See also "DELTA ISLANDS"
	in linkgit:git-pack-objects[1].

pack.deltaCacheSize::
	The maximum memory in bytes used for caching deltas in
	linkgit:git-pack-objects[1] before writing them out to a pack.
	This cache is used to speed up the writing object phase by not
	having to recompute the final delta result once the best match
	for all objects is found.  Repacking large repositories on machines
	which are tight with memory might be badly impacted by this though,
	especially if this cache pushes the system into swapping.
	A value of 0 means no limit. The smallest size of 1 byte may be
	used to virtually disable this cache. Defaults to 256 MiB.

pack.deltaCacheLimit::
	The maximum size of a delta, that is cached in
	linkgit:git-pack-objects[1]. This cache is used to speed up the
	writing object phase by not having to recompute the final delta
	result once the best match for all objects is found.
	Defaults to 1000. Maximum value is 65535.

pack.threads::
	Specifies the number of threads to spawn when searching for best
	delta matches.  This requires that linkgit:git-pack-objects[1]
	be compiled with pthreads otherwise this option is ignored with a
	warning. This is meant to reduce packing time on multiprocessor
	machines. The required amount of memory for the delta search window
	is however multiplied by the number of threads.
	Specifying 0 will cause Git to auto-detect the number of CPU's
	and set the number of threads accordingly.

pack.indexVersion::
	Specify the default pack index version.  Valid values are 1 for
	legacy pack index used by Git versions prior to 1.5.2, and 2 for
	the new pack index with capabilities for packs larger than 4 GB
	as well as proper protection against the repacking of corrupted
	packs.  Version 2 is the default.  Note that version 2 is enforced
	and this config option ignored whenever the corresponding pack is
	larger than 2 GB.
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If you have an old Git that does not understand the version 2 `*.idx` file,
cloning or fetching over a non native protocol (e.g. "http")
that will copy both `*.pack` file and corresponding `*.idx` file from the
other side may give you a repository that cannot be accessed with your
older version of Git. If the `*.pack` file is smaller than 2 GB, however,
you can use linkgit:git-index-pack[1] on the *.pack file to regenerate
the `*.idx` file.

pack.packSizeLimit::
	The maximum size of a pack.  This setting only affects
	packing to a file when repacking, i.e. the git:// protocol
	is unaffected.  It can be overridden by the `--max-pack-size`
	option of linkgit:git-repack[1].  Reaching this limit results
	in the creation of multiple packfiles.
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Note that this option is rarely useful, and may result in a larger total
on-disk size (because Git will not store deltas between packs), as well
as worse runtime performance (object lookup within multiple packs is
slower than a single pack, and optimizations like reachability bitmaps
cannot cope with multiple packs).
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If you need to actively run Git using smaller packfiles (e.g., because your
filesystem does not support large files), this option may help. But if
your goal is to transmit a packfile over a medium that supports limited
sizes (e.g., removable media that cannot store the whole repository),
you are likely better off creating a single large packfile and splitting
it using a generic multi-volume archive tool (e.g., Unix `split`).
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The minimum size allowed is limited to 1 MiB. The default is unlimited.
Common unit suffixes of 'k', 'm', or 'g' are supported.

pack.useBitmaps::
	When true, git will use pack bitmaps (if available) when packing
	to stdout (e.g., during the server side of a fetch). Defaults to
	true. You should not generally need to turn this off unless
	you are debugging pack bitmaps.

pack.useSparse::
	When true, git will default to using the '--sparse' option in
	'git pack-objects' when the '--revs' option is present. This
	algorithm only walks trees that appear in paths that introduce new
	objects. This can have significant performance benefits when
	computing a pack to send a small change. However, it is possible
	that extra objects are added to the pack-file if the included
	commits contain certain types of direct renames. Default is
	`true`.

pack.preferBitmapTips::
	When selecting which commits will receive bitmaps, prefer a
	commit at the tip of any reference that is a suffix of any value
	of this configuration over any other commits in the "selection
	window".
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Note that setting this configuration to `refs/foo` does not mean that
the commits at the tips of `refs/foo/bar` and `refs/foo/baz` will
necessarily be selected. This is because commits are selected for
bitmaps from within a series of windows of variable length.
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If a commit at the tip of any reference which is a suffix of any value
of this configuration is seen in a window, it is immediately given
preference over any other commit in that window.

pack.writeBitmaps (deprecated)::
	This is a deprecated synonym for `repack.writeBitmaps`.

pack.writeBitmapHashCache::
	When true, git will include a "hash cache" section in the bitmap
	index (if one is written). This cache can be used to feed git's
	delta heuristics, potentially leading to better deltas between
	bitmapped and non-bitmapped objects (e.g., when serving a fetch
	between an older, bitmapped pack and objects that have been
	pushed since the last gc). The downside is that it consumes 4
	bytes per object of disk space. Defaults to true.
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When writing a multi-pack reachability bitmap, no new namehashes are
computed; instead, any namehashes stored in an existing bitmap are
permuted into their appropriate location when writing a new bitmap.

pack.writeBitmapLookupTable::
	When true, Git will include a "lookup table" section in the
	bitmap index (if one is written). This table is used to defer
	loading individual bitmaps as late as possible. This can be
	beneficial in repositories that have relatively large bitmap
	indexes. Defaults to false.

pack.writeReverseIndex::
	When true, git will write a corresponding .rev file (see:
	linkgit:gitformat-pack[5])
	for each new packfile that it writes in all places except for
	linkgit:git-fast-import[1] and in the bulk checkin mechanism.
	Defaults to false.