git/t/perf/p2000-sparse-operations.sh
Derrick Stolee c9e40ae8ec p2000: add sparse-index repos
p2000-sparse-operations.sh compares different Git commands in
repositories with many files at HEAD but using sparse-checkout to focus
on a small portion of those files.

Add extra copies of the repository that use the sparse-index format so
we can track how that affects the performance of different commands.

At this point in time, the sparse-index is 100% overhead from the CPU
front, and this is measurable in these tests:

Test
---------------------------------------------------------------
2000.2: git status (full-index-v3)              0.59(0.51+0.12)
2000.3: git status (full-index-v4)              0.59(0.52+0.11)
2000.4: git status (sparse-index-v3)            1.40(1.32+0.12)
2000.5: git status (sparse-index-v4)            1.41(1.36+0.08)
2000.6: git add -A (full-index-v3)              2.32(1.97+0.19)
2000.7: git add -A (full-index-v4)              2.17(1.92+0.14)
2000.8: git add -A (sparse-index-v3)            2.31(2.21+0.15)
2000.9: git add -A (sparse-index-v4)            2.30(2.20+0.13)
2000.10: git add . (full-index-v3)              2.39(2.02+0.20)
2000.11: git add . (full-index-v4)              2.20(1.94+0.16)
2000.12: git add . (sparse-index-v3)            2.36(2.27+0.12)
2000.13: git add . (sparse-index-v4)            2.33(2.21+0.16)
2000.14: git commit -a -m A (full-index-v3)     2.47(2.12+0.20)
2000.15: git commit -a -m A (full-index-v4)     2.26(2.00+0.17)
2000.16: git commit -a -m A (sparse-index-v3)   3.01(2.92+0.16)
2000.17: git commit -a -m A (sparse-index-v4)   3.01(2.94+0.15)

Note that there is very little difference between the v3 and v4 index
formats when the sparse-index is enabled. This is primarily due to the
fact that the relative file sizes are the same, and the command time is
mostly taken up by parsing tree objects to expand the sparse index into
a full one.

With the current file layout, the index file sizes are given by this
table:

       |  full index | sparse index |
       +-------------+--------------+
    v3 |     108 MiB |      1.6 MiB |
    v4 |      80 MiB |      1.2 MiB |

Future updates will improve the performance of Git commands when the
index is sparse.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:49 -07:00

101 lines
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#!/bin/sh
test_description="test performance of Git operations using the index"
. ./perf-lib.sh
test_perf_default_repo
SPARSE_CONE=f2/f4/f1
test_expect_success 'setup repo and indexes' '
git reset --hard HEAD &&
# Remove submodules from the example repo, because our
# duplication of the entire repo creates an unlikely data shape.
if git config --file .gitmodules --get-regexp "submodule.*.path" >modules
then
git rm $(awk "{print \$2}" modules) &&
git commit -m "remove submodules" || return 1
fi &&
echo bogus >a &&
cp a b &&
git add a b &&
git commit -m "level 0" &&
BLOB=$(git rev-parse HEAD:a) &&
OLD_COMMIT=$(git rev-parse HEAD) &&
OLD_TREE=$(git rev-parse HEAD^{tree}) &&
for i in $(test_seq 1 4)
do
cat >in <<-EOF &&
100755 blob $BLOB a
040000 tree $OLD_TREE f1
040000 tree $OLD_TREE f2
040000 tree $OLD_TREE f3
040000 tree $OLD_TREE f4
EOF
NEW_TREE=$(git mktree <in) &&
NEW_COMMIT=$(git commit-tree $NEW_TREE -p $OLD_COMMIT -m "level $i") &&
OLD_TREE=$NEW_TREE &&
OLD_COMMIT=$NEW_COMMIT || return 1
done &&
git sparse-checkout init --cone &&
git branch -f wide $OLD_COMMIT &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . full-index-v3 &&
(
cd full-index-v3 &&
git sparse-checkout init --cone &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 3 &&
git update-index --index-version=3
) &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . full-index-v4 &&
(
cd full-index-v4 &&
git sparse-checkout init --cone &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 4 &&
git update-index --index-version=4
) &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . sparse-index-v3 &&
(
cd sparse-index-v3 &&
git sparse-checkout init --cone --sparse-index &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 3 &&
git update-index --index-version=3
) &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . sparse-index-v4 &&
(
cd sparse-index-v4 &&
git sparse-checkout init --cone --sparse-index &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 4 &&
git update-index --index-version=4
)
'
test_perf_on_all () {
command="$@"
for repo in full-index-v3 full-index-v4 \
sparse-index-v3 sparse-index-v4
do
test_perf "$command ($repo)" "
(
cd $repo &&
echo >>$SPARSE_CONE/a &&
$command
)
"
done
}
test_perf_on_all git status
test_perf_on_all git add -A
test_perf_on_all git add .
test_perf_on_all git commit -a -m A
test_done