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authorWu Zhangjin <wuzhangjin@gmail.com>2010-10-27 18:24:34 +0200
committerSteven Rostedt <rostedt@goodmis.org>2010-11-18 23:16:05 +0100
commit45677454dd6d128608117abe7dcd2bdfdd7cdf72 (patch)
tree61cad49e7d358bfb5c7c23b535d8b7094f89c116 /kernel/printk.c
parentMerge branch 'perf/core' of git://git.kernel.org/pub/scm/linux/kernel/git/fre... (diff)
downloadlinux-45677454dd6d128608117abe7dcd2bdfdd7cdf72.tar.xz
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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>
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