[v2] coccicheck: process every source file at once
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Message ID 20181002200353.13412-1-jacob.e.keller@intel.com
State New
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  • [v2] coccicheck: process every source file at once
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Commit Message

Jacob Keller Oct. 2, 2018, 8:03 p.m. UTC
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(-)

Comments

Jacob Keller Oct. 2, 2018, 8:04 p.m. UTC | #1
On Tue, Oct 2, 2018 at 1:03 PM Jacob Keller <jacob.e.keller@intel.com> wrote:
>
> 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

Patch
diff mbox series

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; \