Re: [PATCH] perf autodep: Remove strlcpy feature check, add __weakstrlcpy implementation

From: Ingo Molnar
Date: Tue Oct 01 2013 - 11:28:15 EST



Ok, this should be my final perf-build speedup patch.

With this patch and all the other patches applied perf delta-builds very
fast now - an empty re-build takes just 0.2 seconds:

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

real 0m0.207s
user 0m0.130s
sys 0m0.034s

and the rebuild after a single .c file was changed is just 1.8 seconds:

comet:~/tip/tools/perf> touch perf.c; time make

real 0m1.892s
user 0m1.495s
sys 0m0.337s

Without the changes this used to be 9.4 seconds:

comet:~/tip/tools/perf> touch perf.c; time make

real 0m9.418s
user 0m8.251s
sys 0m0.996s

which was an eternity! :-)

Thanks,

Ingo

------------------------>
Subject: perf tools: Speed up the final link
From: Ingo Molnar <mingo@xxxxxxxxxx>
Date: Tue Oct 1 17:17:22 CEST 2013

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. ]

Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
tools/perf/Makefile | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

Index: tip/tools/perf/Makefile
===================================================================
--- tip.orig/tools/perf/Makefile
+++ tip/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
@@ -824,7 +828,7 @@ 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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