Re: [PATCH v3] coccicheck: process every source file at once

From: Jacob Keller <jacob.keller@gmail.com>
Date: Oct 5, 2018, 02:17 UTC
Message-ID: <CA+P7+xo=cY2nSHk99CETvba-nZ_jOan5YgpDUjaD=cpTs2ub3A@mail.gmail.com>
In-Reply-To: <CA+P7+xoqKG84n5EMKbajuZoXrOKZMudZ6CT-OKzz8XYyTYaCWQ@mail.gmail.com>

On Tue, Oct 2, 2018 at 1:18 PM Jacob Keller <jacob.keller@gmail.com> wrote:

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>
> On Tue, Oct 2, 2018 at 1:07 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>
> > ---
>
> Forgot to add what changed. I dropped the subshell and "||" bit around
> invoking spatch.
>
> Thanks,
> Jake
>

Junio, do you want me to update the commit message on my side with the memory concerns? Or could you update it to mention memory as a noted trade off.

Thanks, Jake

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>
> >  Makefile | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/Makefile b/Makefile
> > index df1df9db78da..da692ece9e12 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) $(SPATCH_FLAGS) >$@+ 2>$@.log; \
> > +       ret=$$?; \
> >         if test $$ret != 0; \
> >         then \
> >                 cat $@.log; \
> > --
> > 2.18.0.219.gaf81d287a9da
> >