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It can sometimes be useful to see which refs are contributing to the
overall repository size (e.g., does some branch have a bunch of objects
not found elsewhere in history, which indicates that deleting it would
shrink the size of a clone).
You can find that out by generating a list of objects, getting their
sizes from cat-file, and then summing them, like:
git rev-list --objects --no-object-names main..branch
git cat-file --batch-check='%(objectsize:disk)' |
perl -lne '$total += $_; END { print $total }'
Though note that the caveats from git-cat-file(1) apply here. We "blame"
base objects more than their deltas, even though the relationship could
easily be flipped. Still, it can be a useful rough measure.
But one problem is that it's slow to run. Teaching rev-list to sum up
the sizes can be much faster for two reasons:
1. It skips all of the piping of object names and sizes.
2. If bitmaps are in use, for objects that are in the
bitmapped packfile we can skip the oid_object_info()
lookup entirely, and just ask the revindex for the
on-disk size.
This patch implements a --disk-usage option which produces the same
answer in a fraction of the time. Here are some timings using a clone of
torvalds/linux:
[rev-list piped to cat-file, no bitmaps]
$ time git rev-list --objects --no-object-names --all |
git cat-file --buffer --batch-check='%(objectsize:disk)' |
perl -lne '$total += $_; END { print $total }'
1459938510
real 0m29.635s
user 0m38.003s
sys 0m1.093s
[internal, no bitmaps]
$ time git rev-list --disk-usage --objects --all
1459938510
real 0m31.262s
user 0m30.885s
sys 0m0.376s
Even though the wall-clock time is slightly worse due to parallelism,
notice the CPU savings between the two. We saved 21% of the CPU just by
avoiding the pipes.
But the real win is with bitmaps. If we use them without the new option:
[rev-list piped to cat-file, bitmaps]
$ time git rev-list --objects --no-object-names --all --use-bitmap-index |
git cat-file --batch-check='%(objectsize:disk)' |
perl -lne '$total += $_; END { print $total }'
1459938510
real 0m6.244s
user 0m8.452s
sys 0m0.311s
then we're faster to generate the list of objects, but we still spend a
lot of time piping and looking things up. But if we do both together:
[internal, bitmaps]
$ time git rev-list --disk-usage --objects --all --use-bitmap-index
1459938510
real 0m0.219s
user 0m0.169s
sys 0m0.049s
then we get the same answer much faster.
For "--all", that answer will correspond closely to "du objects/pack",
of course. But we're actually checking reachability here, so we're still
fast when we ask for more interesting things:
$ time git rev-list --disk-usage --use-bitmap-index v5.0..v5.10
374798628
real 0m0.429s
user 0m0.356s
sys 0m0.072s
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
51 lines
1.4 KiB
Bash
Executable file
51 lines
1.4 KiB
Bash
Executable file
#!/bin/sh
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test_description='basic tests of rev-list --disk-usage'
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. ./test-lib.sh
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# we want a mix of reachable and unreachable, as well as
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# objects in the bitmapped pack and some outside of it
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test_expect_success 'set up repository' '
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test_commit --no-tag one &&
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test_commit --no-tag two &&
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git repack -adb &&
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git reset --hard HEAD^ &&
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test_commit --no-tag three &&
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test_commit --no-tag four &&
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git reset --hard HEAD^
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'
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# We don't want to hardcode sizes, because they depend on the exact details of
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# packing, zlib, etc. We'll assume that the regular rev-list and cat-file
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# machinery works and compare the --disk-usage output to that.
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disk_usage_slow () {
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git rev-list --no-object-names "$@" |
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git cat-file --batch-check="%(objectsize:disk)" |
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perl -lne '$total += $_; END { print $total}'
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}
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# check behavior with given rev-list options; note that
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# whitespace is not preserved in args
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check_du () {
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args=$*
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test_expect_success "generate expected size ($args)" "
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disk_usage_slow $args >expect
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"
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test_expect_success "rev-list --disk-usage without bitmaps ($args)" "
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git rev-list --disk-usage $args >actual &&
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test_cmp expect actual
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"
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test_expect_success "rev-list --disk-usage with bitmaps ($args)" "
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git rev-list --disk-usage --use-bitmap-index $args >actual &&
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test_cmp expect actual
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"
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}
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check_du HEAD
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check_du --objects HEAD
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check_du --objects HEAD^..HEAD
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test_done
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