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Subject[tip:perf/core] tools/perf/build: Speed up the final link
Commit-ID:  c9404c6650d8f58ce8cf98d4c5581fc5c9e37faf
Gitweb: http://git.kernel.org/tip/c9404c6650d8f58ce8cf98d4c5581fc5c9e37faf
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Tue, 1 Oct 2013 17:17:22 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 9 Oct 2013 08:48:51 +0200

tools/perf/build: Speed up the final link

libtraceevent.a and liblk.a rules have always-missed dependencies,
which causes python.so to be relinked at every build attempt - even
if none of the affected code changes.

This slows down re-builds unnecessarily, by adding more than a second
to the build time:

comet:~/tip/tools/perf> time make

...

SUBDIR /fast/mingo/tip/tools/lib/lk/
make[1]: `liblk.a' is up to date.
SUBDIR /fast/mingo/tip/tools/lib/traceevent/
LINK perf
GEN python/perf.so

real 0m1.701s
user 0m1.338s
sys 0m0.301s

Add the (trivial) dependencies to not force a re-link.

This speeds up an empty re-build enormously:

comet:~/tip/tools/perf> time make

...

real 0m0.207s
user 0m0.134s
sys 0m0.028s

[ This adds some coupling between the build dependencies of
libtraceevent and liblk - but until those stay relatively
simple this should not be an issue. ]

Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/n/tip-wvmlrurufuk6mo1ovtNigguT@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
tools/perf/Makefile | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 6b5452a..df76198 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -669,15 +669,19 @@ $(LIB_FILE): $(LIB_OBJS)
$(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(LIB_OBJS)

# libtraceevent.a
-$(LIBTRACEEVENT):
+TE_SOURCES = $(wildcard $(TRACE_EVENT_DIR)*.[ch])
+
+$(LIBTRACEEVENT): $(TE_SOURCES)
$(QUIET_SUBDIR0)$(TRACE_EVENT_DIR) $(QUIET_SUBDIR1) O=$(OUTPUT) libtraceevent.a

$(LIBTRACEEVENT)-clean:
$(QUIET_SUBDIR0)$(TRACE_EVENT_DIR) $(QUIET_SUBDIR1) O=$(OUTPUT) clean

+LIBLK_SOURCES = $(wildcard $(LK_PATH)*.[ch])
+
# if subdir is set, we've been called from above so target has been built
# already
-$(LIBLK):
+$(LIBLK): $(LIBLK_SOURCES)
ifeq ($(subdir),)
$(QUIET_SUBDIR0)$(LK_DIR) $(QUIET_SUBDIR1) O=$(OUTPUT) liblk.a
endif
@@ -825,6 +829,6 @@ else
GIT-HEAD-PHONY =
endif

-.PHONY: all install clean strip $(LIBTRACEEVENT) $(LIBLK)
+.PHONY: all install clean strip
.PHONY: shell_compatibility_test please_set_SHELL_PATH_to_a_more_modern_shell
.PHONY: $(GIT-HEAD-PHONY) TAGS tags cscope .FORCE-PERF-CFLAGS

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