| Message ID | patch-2.thread-aa7b8d.git-de935bace15a.your-ad-here.call-01533557518-ext-9465@work.hours (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ftrace build improvements | expand |
On Mon, Aug 06, 2018 at 03:17:44PM +0200, Vasily Gorbik wrote: > Currently if CONFIG_FTRACE_MCOUNT_RECORD is enabled -mrecord-mcount > compiler flag support is tested for every Makefile. Good catch. Does it make a measurable compile time difference? > > Top 4 cc-option usages: > 511 -mrecord-mcount > 11 -fno-stack-protector > 9 -Wno-override-init > 2 -fsched-pressure > > To address that move cc-option from scripts/Makefile.build to top Makefile > and export CC_USING_RECORD_MCOUNT to be used in original place. > > While doing that also add -mrecord-mcount to CC_FLAGS_FTRACE (if gcc > actually supports it). > > Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Acked-by: Andi Kleen <ak@linux.intel.com> -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Aug 06, 2018 at 11:07:40AM -0700, Andi Kleen wrote: > On Mon, Aug 06, 2018 at 03:17:44PM +0200, Vasily Gorbik wrote: > > Currently if CONFIG_FTRACE_MCOUNT_RECORD is enabled -mrecord-mcount > > compiler flag support is tested for every Makefile. > > Good catch. Does it make a measurable compile time difference? > A bit more than couple of seconds, but it does make a difference for a delta build: with patch: real 0m9.405s user 0m6.966s sys 0m2.287s without: real 0m12.153s user 0m9.058s sys 0m3.026s with -j48 on s390 24 cores lpar: with patch: real 0m1.949s user 0m7.034s sys 0m2.400s without: real 0m2.255s user 0m9.243s sys 0m3.266s > > > > Top 4 cc-option usages: > > 511 -mrecord-mcount -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Makefile b/Makefile index 503f533277c7..621ebdbfbf89 100644 --- a/Makefile +++ b/Makefile @@ -743,6 +743,13 @@ ifdef CONFIG_FUNCTION_TRACER ifndef CC_FLAGS_FTRACE CC_FLAGS_FTRACE := -pg endif +ifdef CONFIG_FTRACE_MCOUNT_RECORD + # gcc 5 supports generating the mcount tables directly + ifeq ($(call cc-option-yn,-mrecord-mcount),y) + CC_FLAGS_FTRACE += -mrecord-mcount + export CC_USING_RECORD_MCOUNT := 1 + endif +endif ifdef CONFIG_HAVE_FENTRY ifeq ($(call cc-option-yn, -mfentry),y) CC_FLAGS_FTRACE += -mfentry diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 514ed63ff571..42ecb8cf7666 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -206,11 +206,8 @@ cmd_modversions_c = \ endif ifdef CONFIG_FTRACE_MCOUNT_RECORD -# gcc 5 supports generating the mcount tables directly -ifneq ($(call cc-option,-mrecord-mcount,y),y) -KBUILD_CFLAGS += -mrecord-mcount -else -# else do it all manually +ifndef CC_USING_RECORD_MCOUNT +# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl ifdef BUILD_C_RECORDMCOUNT ifeq ("$(origin RECORDMCOUNT_WARN)", "command line") RECORDMCOUNT_FLAGS = -w @@ -239,7 +236,7 @@ cmd_record_mcount = \ "$(CC_FLAGS_FTRACE)" ]; then \ $(sub_cmd_record_mcount) \ fi; -endif # -record-mcount +endif # CC_USING_RECORD_MCOUNT endif # CONFIG_FTRACE_MCOUNT_RECORD ifdef CONFIG_STACK_VALIDATION
Currently if CONFIG_FTRACE_MCOUNT_RECORD is enabled -mrecord-mcount compiler flag support is tested for every Makefile. Top 4 cc-option usages: 511 -mrecord-mcount 11 -fno-stack-protector 9 -Wno-override-init 2 -fsched-pressure To address that move cc-option from scripts/Makefile.build to top Makefile and export CC_USING_RECORD_MCOUNT to be used in original place. While doing that also add -mrecord-mcount to CC_FLAGS_FTRACE (if gcc actually supports it). Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> --- Makefile | 7 +++++++ scripts/Makefile.build | 9 +++------ 2 files changed, 10 insertions(+), 6 deletions(-)