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| author | Wu Zhangjin <wuzhangjin@gmail.com> | 2010-10-28 00:24:34 +0800 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2010-11-18 17:16:05 -0500 |
| commit | 45677454dd6d128608117abe7dcd2bdfdd7cdf72 (patch) | |
| tree | 61cad49e7d358bfb5c7c23b535d8b7094f89c116 /scripts/Makefile.build | |
| parent | ae51ce9061b1ddc0fde363913c932bee5b9bc5fd (diff) | |
| download | lwn-45677454dd6d128608117abe7dcd2bdfdd7cdf72.tar.gz lwn-45677454dd6d128608117abe7dcd2bdfdd7cdf72.zip | |
ftrace: Speed up recordmcount
cmd_record_mcount is used to locate the _mcount symbols in the object
files, only the files compiled with -pg has the _mcount symbol, so, it
is only needed for such files, but the current cmd_record_mcount is used
for all of the object files, so, we need to fix it and speed it up.
Since -pg may be removed by the method used in kernel/trace/Makefile:
ORIG_CFLAGS := $(KBUILD_CFLAGS)
KBUILD_CFLAGS = $(subst -pg,,$(ORIG_CFLAGS))
Or may be removed by the method used in arch/x86/kernel/Makefile:
CFLAGS_REMOVE_file.o = -pg
So, we must check the last variable stores the compiling flags, that is
c_flags(Please refer to cmd_cc_o_c and rule_cc_o_c defined in
scripts/Makefile.build) and since the CFLAGS_REMOVE_file.o is already
filtered in _c_flags(Please refer to scripts/Makefile.lib) and _c_flags
has less symbols, therefore, we only need to check _c_flags.
---------------
Changes from v1:
o Don't touch Makefile for CONFIG_FTRACE_MCOUNT_RECORD is enough
o Use _c_flags intead of KBUILD_CFLAGS to cover CONFIG_REMOVE_file.o = -pg
(feedback from Steven Rostedt <rostedt@goodmis.org>)
Acked-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
LKML-Reference: <3dc8cddf022eb7024f9f2cf857529a15bee8999a.1288196498.git.wuzhangjin@gmail.com>
[ changed if [ .. == .. ] to if [ .. = .. ] to handle dash environments ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'scripts/Makefile.build')
| -rw-r--r-- | scripts/Makefile.build | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 5ad25e17b6cb..4eb99ab34053 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -214,17 +214,22 @@ ifdef BUILD_C_RECORDMCOUNT # The empty.o file is created in the make process in order to determine # the target endianness and word size. It is made before all other C # files, including recordmcount. -cmd_record_mcount = if [ $(@) != "scripts/mod/empty.o" ]; then \ - $(objtree)/scripts/recordmcount "$(@)"; \ - fi; +sub_cmd_record_mcount = \ + if [ $(@) != "scripts/mod/empty.o" ]; then \ + $(objtree)/scripts/recordmcount "$(@)"; \ + fi; else -cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \ +sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \ "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \ "$(if $(CONFIG_64BIT),64,32)" \ "$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \ "$(LD)" "$(NM)" "$(RM)" "$(MV)" \ "$(if $(part-of-module),1,0)" "$(@)"; endif +cmd_record_mcount = \ + if [ "$(findstring -pg,$(_c_flags))" = "-pg" ]; then \ + $(sub_cmd_record_mcount) \ + fi; endif define rule_cc_o_c |