From: Ingo Molnar <mingo@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>, Russ Anderson <rja@sgi.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com
Subject: Re: [patch] mm: speedup in __early_pfn_to_nid
Date: Tue, 26 Mar 2013 09:05:45 +0100 [thread overview]
Message-ID: <20130326080545.GA26852@gmail.com> (raw)
In-Reply-To: <20130325142630.faf41b11416c2e4ac3d61550@linux-foundation.org>
* Andrew Morton <akpm@linux-foundation.org> wrote:
> On Thu, 21 Mar 2013 19:03:21 +0100 Ingo Molnar <mingo@kernel.org> wrote:
>
> > > IMO the local scope is more obvious as this is and should only be
> > > used for caching purposes.
> >
> > It's a pattern we actively avoid in kernel code.
>
> On the contrary, I always encourage people to move the static
> definitions into function scope if possible. So the reader can see the
> identifier's scope without having to search the whole file.
> Unnecessarily giving the identifier file-scope seems weird.
A common solution I use is to move such variables right before the
function itself. That makes the "this function's scope only" aspect pretty
apparent - without the risks of hiding globals amongst local variables.
The other approach is to comment the variables very clearly that they are
really globals as the 'static' keyword is easy to miss while reading
email.
Both solutions are basically just as visible as the solution you prefer -
but more robust.
Anyway, I guess we have to agree to disagree on that, we probably already
spent more energy on discussing this than any worst-case problem the
placement of these variables could ever cause in the future ;-)
Thanks,
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>, Russ Anderson <rja@sgi.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com
Subject: Re: [patch] mm: speedup in __early_pfn_to_nid
Date: Tue, 26 Mar 2013 09:05:45 +0100 [thread overview]
Message-ID: <20130326080545.GA26852@gmail.com> (raw)
In-Reply-To: <20130325142630.faf41b11416c2e4ac3d61550@linux-foundation.org>
* Andrew Morton <akpm@linux-foundation.org> wrote:
> On Thu, 21 Mar 2013 19:03:21 +0100 Ingo Molnar <mingo@kernel.org> wrote:
>
> > > IMO the local scope is more obvious as this is and should only be
> > > used for caching purposes.
> >
> > It's a pattern we actively avoid in kernel code.
>
> On the contrary, I always encourage people to move the static
> definitions into function scope if possible. So the reader can see the
> identifier's scope without having to search the whole file.
> Unnecessarily giving the identifier file-scope seems weird.
A common solution I use is to move such variables right before the
function itself. That makes the "this function's scope only" aspect pretty
apparent - without the risks of hiding globals amongst local variables.
The other approach is to comment the variables very clearly that they are
really globals as the 'static' keyword is easy to miss while reading
email.
Both solutions are basically just as visible as the solution you prefer -
but more robust.
Anyway, I guess we have to agree to disagree on that, we probably already
spent more energy on discussing this than any worst-case problem the
placement of these variables could ever cause in the future ;-)
Thanks,
Ingo
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next prev parent reply other threads:[~2013-03-26 8:05 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-18 15:56 [patch] mm: speedup in __early_pfn_to_nid Russ Anderson
2013-03-18 15:56 ` Russ Anderson
2013-03-19 3:56 ` David Rientjes
2013-03-19 3:56 ` David Rientjes
2013-03-20 22:32 ` Andrew Morton
2013-03-20 22:32 ` Andrew Morton
2013-03-20 22:32 ` Andrew Morton
2013-03-21 10:55 ` Ingo Molnar
2013-03-21 10:55 ` Ingo Molnar
2013-03-21 12:35 ` Michal Hocko
2013-03-21 12:35 ` Michal Hocko
2013-03-21 18:03 ` Ingo Molnar
2013-03-21 18:03 ` Ingo Molnar
2013-03-25 21:26 ` Andrew Morton
2013-03-25 21:26 ` Andrew Morton
2013-03-26 8:05 ` Ingo Molnar [this message]
2013-03-26 8:05 ` Ingo Molnar
2013-03-21 18:40 ` David Rientjes
2013-03-21 18:40 ` David Rientjes
2013-03-22 7:25 ` Ingo Molnar
2013-03-22 7:25 ` Ingo Molnar
2013-03-23 15:29 ` Russ Anderson
2013-03-23 15:29 ` Russ Anderson
2013-03-23 20:37 ` Yinghai Lu
2013-03-25 2:11 ` Lin Feng
2013-03-25 2:11 ` Lin Feng
2013-03-25 21:56 ` Russ Anderson
2013-03-25 21:56 ` Russ Anderson
2013-03-25 22:17 ` Yinghai Lu
2013-03-23 22:24 ` KOSAKI Motohiro
2013-03-23 22:24 ` KOSAKI Motohiro
2013-03-25 0:28 ` David Rientjes
2013-03-25 0:28 ` David Rientjes
2013-03-25 21:34 ` Andrew Morton
2013-03-25 21:34 ` Andrew Morton
2013-03-25 22:36 ` David Rientjes
2013-03-25 22:36 ` David Rientjes
2013-03-25 22:42 ` Andrew Morton
2013-03-25 22:42 ` Andrew Morton
2013-03-24 7:43 ` Ingo Molnar
2013-03-24 7:43 ` Ingo Molnar
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