linux-kernel - Re: [PATCH v2 04/10] mmap locking API: use coccinelle to convert mmap

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Message-ID: <CANN689E-SZhv3tvYc11cNuvGwCi1V1n1ztAnLkUPGvvz7C85dQ@mail.gmail.com>
Date:   Fri, 27 Mar 2020 00:44:29 -0700
From:   Michel Lespinasse <walken@...gle.com>
To:     Markus Elfring <Markus.Elfring@....de>
Cc:     linux-mm <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        Coccinelle <cocci@...teme.lip6.fr>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Matthew Wilcox <willy@...radead.org>,
        Liam Howlett <Liam.Howlett@...cle.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        David Rientjes <rientjes@...gle.com>,
        Hugh Dickins <hughd@...gle.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Peter Zijlstra <peterz@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        Ying Han <yinghan@...gle.com>
Subject: Re: [PATCH v2 04/10] mmap locking API: use coccinelle to convert
 mmap_sem rwsem call sites

On Fri, Mar 27, 2020 at 12:22 AM Markus Elfring <Markus.Elfring@....de> wrote:
>
> > This change converts the existing mmap_sem rwsem calls to use the new
> > mmap locking API instead.
> >
> > The change is generated using coccinelle with the following rules:
>
> Would you like to apply only a single SmPL rule here?

I think this version of the patch is already a single rule, similar to
what you suggested ?

> > // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .
>
> Command parameters like “--jobs 8 --chunksize 1” can be also helpful
> for a parallel execution of the desired software transformation.
>
> I suggest to consider another possibility for a bit of fine-tuning in the shown
> SmPL script if you would eventually care for nicer run time characteristics
> for the application of such a SmPL disjunction.
> How do you think about to order the elements according to a probable
> function call frequency?

I'm not sure it matters that much, as long as it produces the correct
end result. The run takes about 25 seconds before any optimizations,
which I find very acceptable.

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.