Merge branch 'jk/index-pack-w-more-threads'

Long ago, we decided to use 3 threads by default when running the
index-pack task in parallel, which has been adjusted a bit upwards.

* jk/index-pack-w-more-threads:
  index-pack: adjust default threading cap
  p5302: count up to online-cpus for thread tests
  p5302: disable thread-count parameter tests by default

3 files changed, 35 insertions, 23 deletions

diff --git a/t/perf/README b/t/perf/README
index c7b70e2d28..bd649afa97 100644
--- a/t/perf/README
+++ b/t/perf/README
@@ -84,6 +84,15 @@ You can set the following variables (also in your config.mak):
 	probably be about linux.git size for optimal results.
 	Both default to the git.git you are running from.
 
+    GIT_PERF_EXTRA
+	Boolean to enable additional tests. Most test scripts are
+	written to detect regressions between two versions of Git, and
+	the output will compare timings for individual tests between
+	those versions. Some scripts have additional tests which are not
+	run by default, that show patterns within a single version of
+	Git (e.g., performance of index-pack as the number of threads
+	changes). These can be enabled with GIT_PERF_EXTRA.
+
 You can also pass the options taken by ordinary git tests; the most
 useful one is:
 
diff --git a/t/perf/p5302-pack-index.sh b/t/perf/p5302-pack-index.sh
index a9b3e112d9..228593d9ad 100755
--- a/t/perf/p5302-pack-index.sh
+++ b/t/perf/p5302-pack-index.sh
@@ -13,35 +13,36 @@ test_expect_success 'repack' '
 	export PACK
 '
 
-test_perf 'index-pack 0 threads' '
-	rm -rf repo.git &&
-	git init --bare repo.git &&
-	GIT_DIR=repo.git git index-pack --threads=1 --stdin < $PACK
-'
-
-test_perf 'index-pack 1 thread ' '
-	rm -rf repo.git &&
-	git init --bare repo.git &&
-	GIT_DIR=repo.git GIT_FORCE_THREADS=1 git index-pack --threads=1 --stdin < $PACK
+# Rather than counting up and doubling each time, count down from the endpoint,
+# halving each time. That ensures that our final test uses as many threads as
+# CPUs, even if it isn't a power of 2.
+test_expect_success 'set up thread-counting tests' '
+	t=$(test-tool online-cpus) &&
+	threads= &&
+	while test $t -gt 0
+	do
+		threads="$t $threads"
+		t=$((t / 2))
+	done
 '
 
-test_perf 'index-pack 2 threads' '
+test_perf PERF_EXTRA 'index-pack 0 threads' '
 	rm -rf repo.git &&
 	git init --bare repo.git &&
-	GIT_DIR=repo.git git index-pack --threads=2 --stdin < $PACK
-'
-
-test_perf 'index-pack 4 threads' '
-	rm -rf repo.git &&
-	git init --bare repo.git &&
-	GIT_DIR=repo.git git index-pack --threads=4 --stdin < $PACK
+	GIT_DIR=repo.git git index-pack --threads=1 --stdin < $PACK
 '
 
-test_perf 'index-pack 8 threads' '
-	rm -rf repo.git &&
-	git init --bare repo.git &&
-	GIT_DIR=repo.git git index-pack --threads=8 --stdin < $PACK
-'
+for t in $threads
+do
+	THREADS=$t
+	export THREADS
+	test_perf PERF_EXTRA "index-pack $t threads" '
+		rm -rf repo.git &&
+		git init --bare repo.git &&
+		GIT_DIR=repo.git GIT_FORCE_THREADS=1 \
+		git index-pack --threads=$THREADS --stdin <$PACK
+	'
+done
 
 test_perf 'index-pack default number of threads' '
 	rm -rf repo.git &&
diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index 13e389367a..821581a885 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -245,3 +245,5 @@ test_at_end_hook_ () {
 test_export () {
 	export "$@"
 }
+
+test_lazy_prereq PERF_EXTRA 'test_bool_env GIT_PERF_EXTRA false'