From: Josh Triplett <josh@joshtriplett.org>
To: Minho Ban <mhban@samsung.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Paul Turner <pjt@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [RFC/PATCH] Prevent wasting time to find out get_parent_ip
Date: Tue, 24 Apr 2012 16:45:14 -0700 [thread overview]
Message-ID: <20120424234513.GA11841@leaf> (raw)
In-Reply-To: <4F9737CC.6010703@samsung.com>
On Wed, Apr 25, 2012 at 08:31:24AM +0900, Minho Ban wrote:
> On 04/24/2012 09:53 PM, Peter Zijlstra wrote:
> > On Tue, 2012-04-24 at 21:36 +0900, Minho Ban wrote:
> >> trace_preempt_on/off looks empty if PREEMPT_TRACER is off. But actually it is
> >> spending time to find out get_parent_ip(even CALLER_ADDR for some ARCH) which is
> >> in argument. This seems not fair for those who expect to do nothing but increase
> >> or decrease count.
> >
> > You can do the same by making them CPP macros and adding a comment as to
> > why they're macros instead of inlines..
> >
>
> Thank you for pointing this out, certainly macros look better. I'll amend this.
As an alternative, how about making get_parent_ip and its called
functions static inlines? Then the compiler can eliminate them via dead
code elimination.
Or, how about declaring get_parent_ip with the GCC "pure" attribute?
That would tell GCC that it can safely eliminate calls to the function.
- Josh Triplett
next prev parent reply other threads:[~2012-04-24 23:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-24 12:36 [RFC/PATCH] Prevent wasting time to find out get_parent_ip Minho Ban
2012-04-24 12:53 ` Peter Zijlstra
2012-04-24 18:18 ` Steven Rostedt
2012-04-24 23:31 ` Minho Ban
2012-04-24 23:45 ` Josh Triplett [this message]
2012-04-25 3:21 ` Minho Ban
2012-04-25 3:32 ` Steven Rostedt
2012-04-25 6:46 ` Josh Triplett
2012-04-24 18:16 ` Steven Rostedt
2012-04-24 23:54 ` Minho Ban
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