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diff --git a/t/perf/p5303-many-packs.sh b/t/perf/p5303-many-packs.sh
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+#!/bin/sh
+
+test_description='performance with large numbers of packs'
+. ./perf-lib.sh
+
+test_perf_large_repo
+
+# A real many-pack situation would probably come from having a lot of pushes
+# over time. We don't know how big each push would be, but we can fake it by
+# just walking the first-parent chain and having every 5 commits be their own
+# "push". This isn't _entirely_ accurate, as real pushes would have some
+# duplicate objects due to thin-pack fixing, but it's a reasonable
+# approximation.
+#
+# And then all of the rest of the objects can go in a single packfile that
+# represents the state before any of those pushes (actually, we'll generate
+# that first because in such a setup it would be the oldest pack, and we sort
+# the packs by reverse mtime inside git).
+repack_into_n () {
+	rm -rf staging &&
+	mkdir staging &&
+
+	git rev-list --first-parent HEAD |
+	perl -e '
+		my $n = shift;
+		while (<>) {
+			last unless @commits < $n;
+			push @commits, $_ if $. % 5 == 1;
+		}
+		print reverse @commits;
+	' "$1" >pushes &&
+
+	# create base packfile
+	base_pack=$(
+		head -n 1 pushes |
+		git pack-objects --delta-base-offset --revs staging/pack
+	) &&
+	test_export base_pack &&
+
+	# create an empty packfile
+	empty_pack=$(git pack-objects staging/pack </dev/null) &&
+	test_export empty_pack &&
+
+	# and then incrementals between each pair of commits
+	last= &&
+	while read rev
+	do
+		if test -n "$last"; then
+			{
+				echo "$rev" &&
+				echo "^$last"
+			} |
+			git pack-objects --delta-base-offset --revs \
+				staging/pack || return 1
+		fi
+		last=$rev
+	done <pushes &&
+
+	(
+		find staging -type f -name 'pack-*.pack' |
+			xargs -n 1 basename | grep -v "$base_pack" &&
+		printf "^pack-%s.pack\n" $base_pack
+	) >stdin.packs
+
+	# and install the whole thing
+	rm -f .git/objects/pack/* &&
+	mv staging/* .git/objects/pack/
+}
+
+# Pretend we just have a single branch and no reflogs, and that everything is
+# in objects/pack; that makes our fake pack-building via repack_into_n()
+# much simpler.
+test_expect_success 'simplify reachability' '
+	tip=$(git rev-parse --verify HEAD) &&
+	git for-each-ref --format="option no-deref%0adelete %(refname)" |
+	git update-ref --stdin &&
+	rm -rf .git/logs &&
+	git update-ref refs/heads/master $tip &&
+	git symbolic-ref HEAD refs/heads/master &&
+	git repack -ad
+'
+
+for nr_packs in 1 50 1000
+do
+	test_expect_success "create $nr_packs-pack scenario" '
+		repack_into_n $nr_packs
+	'
+
+	test_perf "rev-list ($nr_packs)" '
+		git rev-list --objects --all >/dev/null
+	'
+
+	test_perf "abbrev-commit ($nr_packs)" '
+		git rev-list --abbrev-commit HEAD >/dev/null
+	'
+
+	# This simulates the interesting part of the repack, which is the
+	# actual pack generation, without smudging the on-disk setup
+	# between trials.
+	test_perf "repack ($nr_packs)" '
+		GIT_TEST_FULL_IN_PACK_ARRAY=1 \
+		git pack-objects --keep-true-parents \
+		  --honor-pack-keep --non-empty --all \
+		  --reflog --indexed-objects --delta-base-offset \
+		  --stdout </dev/null >/dev/null
+	'
+
+	test_perf "repack with kept ($nr_packs)" '
+		git pack-objects --keep-true-parents \
+		  --keep-pack=pack-$empty_pack.pack \
+		  --honor-pack-keep --non-empty --all \
+		  --reflog --indexed-objects --delta-base-offset \
+		  --stdout </dev/null >/dev/null
+	'
+
+	test_perf "repack with --stdin-packs ($nr_packs)" '
+		git pack-objects \
+		  --keep-true-parents \
+		  --stdin-packs \
+		  --non-empty \
+		  --delta-base-offset \
+		  --stdout <stdin.packs >/dev/null
+	'
+done
+
+# Measure pack loading with 10,000 packs.
+test_expect_success 'generate lots of packs' '
+	for i in $(test_seq 10000); do
+		echo "blob" &&
+		echo "data <<EOF" &&
+		echo "blob $i" &&
+		echo "EOF" &&
+		echo "checkpoint" || return 1
+	done |
+	git -c fastimport.unpackLimit=0 fast-import
+'
+
+# The purpose of this test is to evaluate load time for a large number
+# of packs while doing as little other work as possible.
+test_perf "load 10,000 packs" '
+	git rev-parse --verify "HEAD^{commit}"
+'
+
+test_done