From c72e3f04b45fb2e50cdd81a50c3778c6a57251d8 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Tue, 1 Oct 2013 16:28:09 +0200 Subject: [PATCH] tools/perf/build: Speed up git-version test on re-make util/PERF-VERSION-GEN is currently executed on every build attempt, and this script can take a lot of time on trees that are at a significant git-distance from Linus's tree: $ time util/PERF-VERSION-GEN real 0m4.343s user 0m4.176s sys 0m0.140s It also takes a lot of time if the Git repository is network attached, etc., because the commands it uses: TAG=$(git describe --abbrev=0 --match "v[0-9].[0-9]*" 2>/dev/null ) has to count commits from the nearest tag and thus has to access (and decompress) every git commit blob on the relevant version path. Even on Linus's tree it takes 0.28 seconds on a fast box to count all the commits and get the git version string: $ time util/PERF-VERSION-GEN real 0m0.279s user 0m0.247s sys 0m0.025s But the version string only has to be regenerated if the git repository's head commit changes. So add a dependency of ../../.git/HEAD and touch the file every time it's regenerated, so that Make's build rules can pick it up and cache the result: make: `PERF-VERSION-FILE' is up to date. real 0m0.184s user 0m0.117s sys 0m0.026s Cc: Arnaldo Carvalho de Melo Cc: Peter Zijlstra Cc: Namhyung Kim Cc: David Ahern Cc: Jiri Olsa Link: http://lkml.kernel.org/n/tip-wvmlrurufuk6mo1ovtNigguT@git.kernel.org Signed-off-by: Ingo Molnar --- tools/perf/Makefile | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/tools/perf/Makefile b/tools/perf/Makefile index 64c043b..6b5452a 100644 --- a/tools/perf/Makefile +++ b/tools/perf/Makefile @@ -70,8 +70,9 @@ ifneq ($(OUTPUT),) #$(info Determined 'OUTPUT' to be $(OUTPUT)) endif -$(OUTPUT)PERF-VERSION-FILE: .FORCE-PERF-VERSION-FILE +$(OUTPUT)PERF-VERSION-FILE: ../../.git/HEAD @$(SHELL_PATH) util/PERF-VERSION-GEN $(OUTPUT) + @touch $(OUTPUT)PERF-VERSION-FILE CC = $(CROSS_COMPILE)gcc AR = $(CROSS_COMPILE)ar @@ -814,6 +815,16 @@ clean: $(LIBTRACEEVENT)-clean $(LIBLK)-clean $(RM) $(OUTPUT)util/*-flex* $(python-clean) +# +# Trick: if ../../.git does not exist - we are building out of tree for example, +# then force version regeneration: +# +ifeq ($(wildcard ../../.git/HEAD),) + GIT-HEAD-PHONY = ../../.git/HEAD +else + GIT-HEAD-PHONY = +endif + .PHONY: all install clean strip $(LIBTRACEEVENT) $(LIBLK) .PHONY: shell_compatibility_test please_set_SHELL_PATH_to_a_more_modern_shell -.PHONY: .FORCE-PERF-VERSION-FILE TAGS tags cscope .FORCE-PERF-CFLAGS +.PHONY: $(GIT-HEAD-PHONY) TAGS tags cscope .FORCE-PERF-CFLAGS -- 2.7.4