From: "H. Peter Anvin" <hpa@zytor.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>,
tglx@linutronix.de, mingo@redhat.com, andi@firstfloor.org,
Frederic Weisbecker <fweisbec@gmail.com>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 6/8] x86/ftrace: Use __pa_symbol instead of __pa on C visible symbols
Date: Fri, 16 Nov 2012 15:06:03 -0800 [thread overview]
Message-ID: <50A6C6DB.2000205@zytor.com> (raw)
In-Reply-To: <1353105926.7586.30.camel@gandalf.local.home>
On 11/16/2012 02:45 PM, Steven Rostedt wrote:
>
> #define __pa(x) __phys_addr((unsigned long)(x))
> #define __pa_symbol(x) __pa(__phys_reloc_hide((unsigned long)(x)))
>
> I'm confused. __pa_symbol() just calls __pa() with some macro magic to
> its parameter. How is this a performance improvement?
>
One of the earlier patches in this series changes __pa_symbol() to avoid
the conditional hidden inside __phys_addr(), since by definition a
symbol can only be on one side of that branch.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-11-16 23:06 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-16 21:52 [PATCH v4 0/8] Improve performance of VM translation on x86_64 Alexander Duyck
2012-11-16 21:53 ` [PATCH v4 1/8] x86: Move some contents of page_64_types.h into pgtable_64.h and page_64.h Alexander Duyck
2012-11-17 0:22 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2012-11-17 0:30 ` Yinghai Lu
2012-11-17 0:42 ` H. Peter Anvin
2012-11-17 0:49 ` tip-bot for Alexander Duyck
2012-11-16 21:53 ` [PATCH v4 2/8] x86: Improve __phys_addr performance by making use of carry flags and inlining Alexander Duyck
2012-11-17 0:23 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2012-11-17 0:50 ` tip-bot for Alexander Duyck
2012-11-16 21:55 ` [PATCH v4 3/8] x86: Make it so that __pa_symbol can only process kernel symbols on x86_64 Alexander Duyck
2012-11-17 0:24 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2012-11-17 0:51 ` tip-bot for Alexander Duyck
2012-11-16 21:56 ` [PATCH v4 4/8] x86: Drop 4 unnecessary calls to __pa_symbol Alexander Duyck
2012-11-17 0:25 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2012-11-17 0:52 ` tip-bot for Alexander Duyck
2012-11-16 21:57 ` [PATCH v4 5/8] x86: Use __pa_symbol instead of __pa on C visible symbols Alexander Duyck
2012-11-17 0:26 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2012-11-17 0:53 ` tip-bot for Alexander Duyck
2012-11-16 21:57 ` [PATCH v4 6/8] x86/ftrace: " Alexander Duyck
2012-11-16 22:20 ` Steven Rostedt
2012-11-16 22:25 ` H. Peter Anvin
2012-11-16 22:45 ` Steven Rostedt
2012-11-16 23:06 ` H. Peter Anvin [this message]
2012-11-16 23:20 ` Alexander Duyck
2012-11-16 23:30 ` Steven Rostedt
2012-11-17 0:27 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2012-11-17 0:54 ` tip-bot for Alexander Duyck
2012-11-16 21:57 ` [PATCH v4 7/8] x86/acpi: " Alexander Duyck
2012-11-16 22:02 ` Pavel Machek
2012-11-17 0:28 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2012-11-17 0:55 ` tip-bot for Alexander Duyck
2012-11-16 21:58 ` [PATCH v4 8/8] x86/lguest: " Alexander Duyck
2012-11-17 0:30 ` [tip:x86/mm] " tip-bot for Alexander Duyck
2013-01-26 1:50 ` tip-bot for Alexander Duyck
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