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dc5d40f5bc
When running 'read-tree' with a single tree and no prefix,
'prime_cache_tree()' is called after the tree is unpacked. In that
situation, skip a redundant call to 'cache_tree_update()' in
'unpack_trees()' by enabling the 'skip_cache_tree_update' unpack option.
Removing the redundant cache tree update provides a substantial performance
improvement to 'git read-tree <tree-ish>', as shown by a test added to
'p0006-read-tree-checkout.sh':
Test before after
----------------------------------------------------------------------
read-tree br_ballast_plus_1 3.94(1.80+1.57) 3.00(1.14+1.28) -23.9%
Note that the 'read-tree' in 't1022-read-tree-partial-clone.sh' is updated
to read two trees, rather than one. The test was first introduced in
d3da223f22 (cache-tree: prefetch in partial clone read-tree, 2021-07-23) to
exercise the 'cache_tree_update()' code path, as used in 'git merge'. Since
this patch drops the call to 'cache_tree_update()' in single-tree 'git
read-tree', change the test to use the two-tree variant so that
'cache_tree_update()' is called as intended.
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
75 lines
2.2 KiB
Bash
Executable file
75 lines
2.2 KiB
Bash
Executable file
#!/bin/sh
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#
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# This test measures the performance of various read-tree
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# and checkout operations. It is primarily interested in
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# the algorithmic costs of index operations and recursive
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# tree traversal -- and NOT disk I/O on thousands of files.
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test_description="Tests performance of read-tree"
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. ./perf-lib.sh
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test_perf_default_repo
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# If the test repo was generated by ./repos/many-files.sh
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# then we know something about the data shape and branches,
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# so we can isolate testing to the ballast-related commits
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# and setup sparse-checkout so we don't have to populate
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# the ballast files and directories.
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#
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# Otherwise, we make some general assumptions about the
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# repo and consider the entire history of the current
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# branch to be the ballast.
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test_expect_success "setup repo" '
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if git rev-parse --verify refs/heads/p0006-ballast^{commit}
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then
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echo Assuming synthetic repo from many-files.sh &&
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git branch br_base master &&
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git branch br_ballast p0006-ballast^ &&
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git branch br_ballast_alias p0006-ballast^ &&
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git branch br_ballast_plus_1 p0006-ballast &&
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git config --local core.sparsecheckout 1 &&
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cat >.git/info/sparse-checkout <<-EOF
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/*
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!ballast/*
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EOF
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else
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echo Assuming non-synthetic repo... &&
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git branch br_base $(git rev-list HEAD | tail -n 1) &&
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git branch br_ballast HEAD^ || error "no ancestor commit from current head" &&
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git branch br_ballast_alias HEAD^ &&
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git branch br_ballast_plus_1 HEAD
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fi &&
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git checkout -q br_ballast &&
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nr_files=$(git ls-files | wc -l)
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'
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test_perf "read-tree br_base br_ballast ($nr_files)" '
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git read-tree -n -m br_base br_ballast
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'
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test_perf "read-tree br_ballast_plus_1 ($nr_files)" '
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# Run read-tree 100 times for clearer performance results & comparisons
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for i in $(test_seq 100)
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do
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git read-tree -n -m br_ballast_plus_1 || return 1
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done
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'
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test_perf "switch between br_base br_ballast ($nr_files)" '
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git checkout -q br_base &&
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git checkout -q br_ballast
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'
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test_perf "switch between br_ballast br_ballast_plus_1 ($nr_files)" '
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git checkout -q br_ballast_plus_1 &&
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git checkout -q br_ballast
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'
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test_perf "switch between aliases ($nr_files)" '
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git checkout -q br_ballast_alias &&
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git checkout -q br_ballast
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'
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test_done
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