1 files changed, 75 insertions, 0 deletions
diff --git a/t/perf/p0006-read-tree-checkout.sh b/t/perf/p0006-read-tree-checkout.sh
new file mode 100755
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+++ b/t/perf/p0006-read-tree-checkout.sh
@@ -0,0 +1,75 @@
+#!/bin/sh
+#
+# This test measures the performance of various read-tree
+# and checkout operations.  It is primarily interested in
+# the algorithmic costs of index operations and recursive
+# tree traversal -- and NOT disk I/O on thousands of files.
+
+test_description="Tests performance of read-tree"
+
+. ./perf-lib.sh
+
+test_perf_default_repo
+
+# If the test repo was generated by ./repos/many-files.sh
+# then we know something about the data shape and branches,
+# so we can isolate testing to the ballast-related commits
+# and setup sparse-checkout so we don't have to populate
+# the ballast files and directories.
+#
+# Otherwise, we make some general assumptions about the
+# repo and consider the entire history of the current
+# branch to be the ballast.
+
+test_expect_success "setup repo" '
+	if git rev-parse --verify refs/heads/p0006-ballast^{commit}
+	then
+		echo Assuming synthetic repo from many-files.sh &&
+		git branch br_base            master &&
+		git branch br_ballast         p0006-ballast^ &&
+		git branch br_ballast_alias   p0006-ballast^ &&
+		git branch br_ballast_plus_1  p0006-ballast &&
+		git config --local core.sparsecheckout 1 &&
+		cat >.git/info/sparse-checkout <<-EOF
+		/*
+		!ballast/*
+		EOF
+	else
+		echo Assuming non-synthetic repo... &&
+		git branch br_base            $(git rev-list HEAD | tail -n 1) &&
+		git branch br_ballast         HEAD^ || error "no ancestor commit from current head" &&
+		git branch br_ballast_alias   HEAD^ &&
+		git branch br_ballast_plus_1  HEAD
+	fi &&
+	git checkout -q br_ballast &&
+	nr_files=$(git ls-files | wc -l)
+'
+
+test_perf "read-tree br_base br_ballast ($nr_files)" '
+	git read-tree -n -m br_base br_ballast
+'
+
+test_perf "read-tree br_ballast_plus_1 ($nr_files)" '
+	# Run read-tree 100 times for clearer performance results & comparisons
+	for i in  $(test_seq 100)
+	do
+		git read-tree -n -m br_ballast_plus_1 || return 1
+	done
+'
+
+test_perf "switch between br_base br_ballast ($nr_files)" '
+	git checkout -q br_base &&
+	git checkout -q br_ballast
+'
+
+test_perf "switch between br_ballast br_ballast_plus_1 ($nr_files)" '
+	git checkout -q br_ballast_plus_1 &&
+	git checkout -q br_ballast
+'
+
+test_perf "switch between aliases ($nr_files)" '
+	git checkout -q br_ballast_alias &&
+	git checkout -q br_ballast
+'
+
+test_done