[PATCH v2] coccicheck: process every source file at once

Jacob Keller· Oct 2, 2018, 20:03 UTC · lore

From: Jacob Keller <jacob.keller@gmail.com>

make coccicheck is used in order to apply coccinelle semantic patches, and see if any of the transformations found within contrib/coccinelle/ can be applied to the current code base.

Pass every file to a single invocation of spatch, instead of running spatch once per source file.

This reduces the time required to run make coccicheck by a significant amount of time:

Prior timing of make coccicheck
  real    6m14.090s
  user    25m2.606s
  sys     1m22.919s

New timing of make coccicheck
  real    1m36.580s
  user    7m55.933s
  sys     0m18.219s

This is nearly a 4x decrease in the time required to run make coccicheck. This is due to the overhead of restarting spatch for every file. By processing all files at once, we can amortize this startup cost across the total number of files, rather than paying it once per file.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
---
 Makefile | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Show changes to Makefile +2 −4

diff --git a/Makefile b/Makefile
index df1df9db78da..b9947f3f51ec 100644
--- a/Makefile
+++ b/Makefile
@@ -2715,10 +2715,8 @@ endif
 %.cocci.patch: %.cocci $(COCCI_SOURCES)
 	@echo '    ' SPATCH $<; \
 	ret=0; \
-	for f in $(COCCI_SOURCES); do \
-		$(SPATCH) --sp-file $< $$f $(SPATCH_FLAGS) || \
-			{ ret=$$?; break; }; \
-	done >$@+ 2>$@.log; \
+	( $(SPATCH) --sp-file $< $(COCCI_SOURCES) $(SPATCH_FLAGS) || \
+		{ ret=$$?; }; ) >$@+ 2>$@.log; \
 	if test $$ret != 0; \
 	then \
 		cat $@.log; \

-- 
2.18.0.219.gaf81d287a9da

Jacob Keller· Oct 2, 2018, 20:04 UTC · re: Jacob Keller · lore

Re: [PATCH v2] coccicheck: process every source file at once

On Tue, Oct 2, 2018 at 1:03 PM Jacob Keller <jacob.e.keller@intel.com> wrote:

Show 30 quoted lines

>
> From: Jacob Keller <jacob.keller@gmail.com>
>
> make coccicheck is used in order to apply coccinelle semantic patches,
> and see if any of the transformations found within contrib/coccinelle/
> can be applied to the current code base.
>
> Pass every file to a single invocation of spatch, instead of running
> spatch once per source file.
>
> This reduces the time required to run make coccicheck by a significant
> amount of time:
>
> Prior timing of make coccicheck
>   real    6m14.090s
>   user    25m2.606s
>   sys     1m22.919s
>
> New timing of make coccicheck
>   real    1m36.580s
>   user    7m55.933s
>   sys     0m18.219s
>
> This is nearly a 4x decrease in the time required to run make
> coccicheck. This is due to the overhead of restarting spatch for every
> file. By processing all files at once, we can amortize this startup cost
> across the total number of files, rather than paying it once per file.
>
> Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
> ---

Woops, ignore this version, it doesn't quite work.

Thanks, Jake

v2coccicheck: process every source file at once