From 94fcf0e85207979e3a7b35ad348cdd6b7ab42058 Mon Sep 17 00:00:00 2001 From: Victoria Dye Date: Thu, 10 Nov 2022 19:06:01 +0000 Subject: cache-tree: add perf test comparing update and prime MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add a performance test comparing the execution times of 'prime_cache_tree()' and 'cache_tree_update(_, WRITE_TREE_SILENT | WRITE_TREE_REPAIR)'. The goal of comparing these two is to identify which is the faster method for rebuilding an invalid cache tree, ultimately to remove one when both are (reundantly) called in immediate succession. Both methods are fast, so the new tests in 'p0090-cache-tree.sh' must call each tested function multiple times to ensure the reported times (to 0.01s resolution) convey the differences between them. The tests compare the timing of a 'test-tool cache-tree' run as a no-op (to capture a baseline for the overhead associated with running the tool), 'cache_tree_update()', and 'prime_cache_tree()' on four scenarios: - A completely valid cache tree - A cache tree with 2 invalid paths - A cache tree with 50 invalid paths - A completely empty cache tree Example results: Test this tree ----------------------------------------------------------- 0090.2: no-op, clean 1.27(0.48+0.52) 0090.3: prime_cache_tree, clean 2.02(0.83+0.85) 0090.4: cache_tree_update, clean 1.30(0.49+0.54) 0090.5: no-op, invalidate 2 1.29(0.48+0.54) 0090.6: prime_cache_tree, invalidate 2 1.98(0.81+0.83) 0090.7: cache_tree_update, invalidate 2 2.12(0.94+0.86) 0090.8: no-op, invalidate 50 1.32(0.50+0.55) 0090.9: prime_cache_tree, invalidate 50 2.10(0.86+0.89) 0090.10: cache_tree_update, invalidate 50 2.35(1.14+0.90) 0090.11: no-op, empty 1.33(0.50+0.54) 0090.12: prime_cache_tree, empty 2.04(0.84+0.87) 0090.13: cache_tree_update, empty 2.51(1.27+0.92) These timings show that, while 'cache_tree_update()' is faster when the cache tree is completely valid, it is equal to or slower than 'prime_cache_tree()' when there are any invalid paths. Since the redundant calls are mostly in scenarios where the cache tree will be at least partially invalid (e.g., 'git reset --hard'), 'prime_cache_tree()' will likely perform better than 'cache_tree_update()' in typical cases. Helped-by: SZEDER Gábor Signed-off-by: Victoria Dye Signed-off-by: Taylor Blau --- Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'Makefile') diff --git a/Makefile b/Makefile index 4927379184..3639c7c2a9 100644 --- a/Makefile +++ b/Makefile @@ -723,6 +723,7 @@ TEST_BUILTINS_OBJS += test-advise.o TEST_BUILTINS_OBJS += test-bitmap.o TEST_BUILTINS_OBJS += test-bloom.o TEST_BUILTINS_OBJS += test-bundle-uri.o +TEST_BUILTINS_OBJS += test-cache-tree.o TEST_BUILTINS_OBJS += test-chmtime.o TEST_BUILTINS_OBJS += test-config.o TEST_BUILTINS_OBJS += test-crontab.o -- cgit v1.3