From: Andrew Morton <akpm@linux-foundation.org>
To: Daniel Santos <daniel.santos@pobox.com>
Cc: Daniel Santos <danielfsantos@att.net>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, torvalds@linux-foundation.org
Subject: Re: Please be aware that __always_inline doesn't mean "always inline"!
Date: Wed, 26 Sep 2012 16:50:44 -0700 [thread overview]
Message-ID: <20120926165044.46b8f7d6.akpm@linux-foundation.org> (raw)
In-Reply-To: <50638DCC.5040506@att.net>
On Wed, 26 Sep 2012 18:20:44 -0500
Daniel Santos <danielfsantos@att.net> wrote:
> I've noticed that there's a lot of misperception about the meaning of
> the __always_inline, or more specifically,
> __attribute__((always_inline)), which does not actually cause the
> function to always be inlined. Rather, it *allows* gcc to inline the
> function, even when compiling without optimizations. Here is the
> description of the attribute from gcc's docs
> (http://gcc.gnu.org/onlinedocs/gcc-4.7.2/gcc/Function-Attributes.html)
>
> always_inline
> Generally, functions are not inlined unless optimization is specified.
> For functions declared inline, this attribute inlines the function even
> if no optimization level was specified.
>
> This would even appear to imply that such functions aren't even marked
> as "inline" (something I wasn't aware of until today). The only
> mechanism I'm currently aware of to force gcc to inline a function is
> the flatten attribute (see https://lkml.org/lkml/2012/9/25/643) which
> works backwards, you declare it on the calling function, and it forces
> gcc to inline all functions (marked as inline) that it calls.
As I mentioned in the other thread, the __always_inline's in fs/namei.c
(at least) are doing exactly what we want them to do, so some more
investigation is needed here?
next prev parent reply other threads:[~2012-09-26 23:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-26 23:20 Please be aware that __always_inline doesn't mean "always inline"! Daniel Santos
2012-09-26 23:50 ` Andrew Morton [this message]
2012-09-27 0:03 ` Daniel Santos
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