From d417bf474f04f8a5a1e09b431abbd9bad9af4952 Mon Sep 17 00:00:00 2001 From: Colin Cross Date: Wed, 8 Jul 2020 15:51:37 -0700 Subject: [PATCH] Document critical path in perf.md Test: none Change-Id: I7de9b98fea67084ec5b5ce5429f0a8f976341439 --- docs/perf.md | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/docs/perf.md b/docs/perf.md index 538adffb5..86a27b43f 100644 --- a/docs/perf.md +++ b/docs/perf.md @@ -12,6 +12,41 @@ are stored in `soong.#.log` and `verbose.#.log.gz`. ![trace example](./trace_example.png) +### Critical path + +soong_ui logs the wall time of the longest dependency chain compared to the +elapsed wall time in `$OUT_DIR/soong.log`. For example: +``` +critical path took 3m10s +elapsed time 5m16s +perfect parallelism ratio 60% +critical path: + 0:00 build out/target/product/generic_arm64/obj/FAKE/sepolicy_neverallows_intermediates/policy_2.conf + 0:04 build out/target/product/generic_arm64/obj/FAKE/sepolicy_neverallows_intermediates/sepolicy_neverallows + 0:13 build out/target/product/generic_arm64/obj/ETC/plat_sepolicy.cil_intermediates/plat_sepolicy.cil + 0:01 build out/target/product/generic_arm64/obj/ETC/plat_pub_versioned.cil_intermediates/plat_pub_versioned.cil + 0:02 build out/target/product/generic_arm64/obj/ETC/vendor_sepolicy.cil_intermediates/vendor_sepolicy.cil + 0:16 build out/target/product/generic_arm64/obj/ETC/sepolicy_intermediates/sepolicy + 0:00 build out/target/product/generic_arm64/obj/ETC/plat_seapp_contexts_intermediates/plat_seapp_contexts + 0:00 Install: out/target/product/generic_arm64/system/etc/selinux/plat_seapp_contexts + 0:02 build out/target/product/generic_arm64/obj/NOTICE.txt + 0:00 build out/target/product/generic_arm64/obj/NOTICE.xml.gz + 0:00 build out/target/product/generic_arm64/system/etc/NOTICE.xml.gz + 0:01 Installed file list: out/target/product/generic_arm64/installed-files.txt + 1:00 Target system fs image: out/target/product/generic_arm64/obj/PACKAGING/systemimage_intermediates/system.img + 0:01 Install system fs image: out/target/product/generic_arm64/system.img + 0:01 Target vbmeta image: out/target/product/generic_arm64/vbmeta.img + 1:26 Package target files: out/target/product/generic_arm64/obj/PACKAGING/target_files_intermediates/aosp_arm64-target_files-6663974.zip + 0:01 Package: out/target/product/generic_arm64/aosp_arm64-img-6663974.zip + 0:01 Dist: /buildbot/dist_dirs/aosp-master-linux-aosp_arm64-userdebug/6663974/aosp_arm64-img-6663974.zip +``` + +If the elapsed time is much longer than the critical path then additional +parallelism on the build machine will improve total build times. If there are +long individual times listed in the critical path then improving build times +for those steps or adjusting dependencies so that those steps can run earlier +in the build graph will improve total build times. + ### Soong Soong can be traced and profiled using the standard Go tools. It understands