From: Johannes Berg <johannes@sipsolutions.net>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: Hauke Mehrtens <hauke@hauke-m.de>,
"backports@vger.kernel.org" <backports@vger.kernel.org>,
cocci@systeme.lip6.fr
Subject: Re: [Cocci] 0079-netdev-destructor.cocci very slow
Date: Wed, 19 Sep 2018 11:02:09 +0200 [thread overview]
Message-ID: <1537347729.10305.10.camel@sipsolutions.net> (raw)
In-Reply-To: <alpine.DEB.2.20.1809191047200.4106@hadrien>
On Wed, 2018-09-19 at 10:49 +0200, Julia Lawall wrote:
> > > It looks like coccinelle already does such a grep when I remove the <--
> > > --> from the patch, because this is about 100 times faster.
> >
> > Good point, not sure why it doesn't do that with the <... ...>?
>
> Because <... ...> means 0 or more of what is inside.
Oops, right.
> <+... ...+> looks for one or more and may be faster.
Indeed, it's two orders of magnitude faster (running it on just
drivers/net/wireless goes from ~500 to ~2s for me) as it can throw away
almost all files immediately.
> On the other hand, it ensures that
> there is one or more, which can also be expensive.
That doesn't really matter all that much for us - the (really) expensive
part is running it on all files that don't even contain it at all.
> It could be better to just have a rule:
>
> @worthwhile@
> @@
>
> (
> functions(...)
> >
>
> you(...)
> >
>
> like(...)
> )
>
> and then have the <... ...> rule depend on worthwhile.
Good idea too.
Thanks!
johannes
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prev parent reply other threads:[~2018-09-19 14:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-17 21:55 0079-netdev-destructor.cocci very slow Hauke Mehrtens
2018-09-18 9:22 ` Johannes Berg
2018-09-18 21:52 ` Hauke Mehrtens
2018-09-19 8:43 ` Johannes Berg
2018-09-19 8:49 ` [Cocci] " Julia Lawall
2018-09-19 9:02 ` Johannes Berg [this message]
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