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From: Steven Rostedt <rostedt@goodmis.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Li Zefan <lizf@cn.fujitsu.com>
Subject: Re: [RFC][PATCH] tracing/module: Move tracepoint out of module.h
Date: Thu, 26 Jan 2012 09:04:29 -0500	[thread overview]
Message-ID: <1327586669.22710.89.camel@gandalf.stny.rr.com> (raw)
In-Reply-To: <20120126135504.GA13107@elte.hu>

[ Added Li who added the original tracepoint ]

On Thu, 2012-01-26 at 14:55 +0100, Ingo Molnar wrote:
> * Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > On Thu, 2012-01-26 at 11:28 +0100, Ingo Molnar wrote:
> > 
> > > How much more do we save if we move all of try_module_get() out 
> > > of line? It still seems a rather thick inline function with 
> > > preempt section and all. I'd *really* suggest that it should all 
> > > be uninlined.
> > > 
> > 
> > Here's the #'s
> > 
> >    text	   data	    bss	    dec	    hex	filename
> > 7489488	2249584	9719808	19458880	128eb40	vmlinux-prepatch
> >    text	   data	    bss	    dec	    hex	filename
> > 7482458	2248048	9719808	19450314	128c9ca	vmlinux-postpatch
> >    text	   data	    bss	    dec	    hex	filename
> > 7477393	2248080	9719808	19445281	128b621	vmlinux-updatedpatch
> > 
> > Thus we get an additional 5k it seems, for a total of 13k savings.
> > 
> > The below patch is what I used. Note, since the tracepoint 
> > requires the instruction pointer, I created stub versions that 
> > call a "do_" version of the function to pass in the local 
> > instruction counter.
> 
> Hm, why does this tracepoint include a flat RIP? It's pretty 
> superfluous as there's various other (orghogonal) ways to get at 
> the RIP.
> 
> If the field is needed for compatibility then lets set it to 
> zero at the tracepoint level and not burden the module.h 
> hotpath.

Perhaps I could use "__builtin_return_address(0)" instead. I'll try that
out. That way, we don't burden the module hotpath, and we keep the old
behavior.

-- Steve



  reply	other threads:[~2012-01-26 14:04 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-16 22:57 [PATCH][GIT PULL][v3.3] tracing: Add header wrappers event_headers_start.h and event_headers_end.h Steven Rostedt
2012-01-17  9:54 ` Ingo Molnar
2012-01-17 13:32   ` Steven Rostedt
2012-01-18 12:07     ` Ingo Molnar
2012-01-18 17:56       ` Steven Rostedt
2012-01-22 22:59         ` Rusty Russell
2012-01-26  2:41           ` [RFC][PATCH] tracing/module: Move tracepoint out of module.h Steven Rostedt
2012-01-26  2:45             ` Steven Rostedt
2012-01-26 10:28             ` Ingo Molnar
2012-01-26 13:52               ` Steven Rostedt
2012-01-26 13:55                 ` Ingo Molnar
2012-01-26 14:04                   ` Steven Rostedt [this message]
2012-01-26 14:07                     ` Steven Rostedt
2012-01-26 14:36                     ` Steven Rostedt
2012-01-26 18:39                       ` Ingo Molnar
2012-01-27  3:02                         ` Rusty Russell
2012-01-30 11:52                           ` Steven Rostedt
2012-01-30 17:28                             ` Steven Rostedt
2012-01-31  3:58                             ` Rusty Russell
2012-01-31 12:20                               ` Ingo Molnar
2012-01-31 12:50                                 ` Steven Rostedt
2012-02-01  6:48                                   ` Rusty Russell
2012-02-01 13:27                                     ` Steven Rostedt
2012-02-01 13:49                                     ` Ingo Molnar
2012-02-01 14:25                                       ` Steven Rostedt
2012-03-29  4:22                                     ` Eric Dumazet
2012-03-29  5:24                                       ` Rusty Russell
2012-02-01  1:10                                 ` Rusty Russell
2012-02-01  7:09                                   ` Ingo Molnar
2012-01-30  6:40                       ` Li Zefan
2012-02-17 13:46       ` [tip:perf/core] tracing/softirq: Move __raise_softirq_irqoff() out of header tip-bot for Steven Rostedt

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