[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <49726C56.6080905@zytor.com>
Date: Sat, 17 Jan 2009 15:40:06 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
CC: Kyle McMartin <kyle@...radead.org>, Ingo Molnar <mingo@...e.hu>,
Mikael Pettersson <mikpe@...uu.se>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: "eliminate warn_on_slowpath()" change causes many gcc-3.2.3 warnings
Linus Torvalds wrote:
>
> Don't do this. That just forces a load off a complex pointer instead, with
> no upsides. At least if it was
>
> extern const char warn_slowpath_nofmt[];
>
> it would only load the pointer itself, which is still a fairly expensive
> op, but at least doesn't require the extra memory load.
>
> But you'd be better off jusst making it something like
>
> #define NO_FMT ((const char *)(-1))
>
> instead, which is really much more obvious, and doesn't need any of that
> "get a pointer" overhead.
>
At least on x86, the two ops should be the same cost?
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists