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From: Ingo Molnar <mingo@elte.hu>
To: linux-kernel@vger.kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Peter Zijlstra" <a.p.zijlstra@chello.nl>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Jan Beulich" <JBeulich@suse.com>,
	"Arjan van de Ven" <arjan@infradead.org>,
	"Alexander van Heukelum" <heukelum@fastmail.fm>,
	"Jeremy Fitzhardinge" <jeremy@goop.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>
Subject: Re: [PATCH] x86: Use -m-omit-leaf-frame-pointer to shrink text size
Date: Fri, 16 Dec 2011 09:53:00 +0100	[thread overview]
Message-ID: <20111216085259.GA2338@elte.hu> (raw)
In-Reply-To: <20111216081915.GA28288@elte.hu>


* Ingo Molnar <mingo@elte.hu> wrote:

> [...]
> 
> The call-chains are still intact for quality backtraces and 
> for call-chain profiling (perf record -g), as the backtrace 
> walker can deduct the full backtrace from the RIP of a leaf 
> function and the parent chain.

Hm, noticed one complication while looking at annotated assembly 
code in perf top. Code doing function calls from within asm() is 
incorrectly marked 'leaf' by GCC:

ffffffff812b82d8 <arch_local_save_flags>:
ffffffff812b82d8:       ff 14 25 00 d9 c1 81    callq  *0xffffffff81c1d900
ffffffff812b82df:       c3                      retq   

So all the paravirt details will have to be fixed, so that GCC 
is able to see that there's a real function call done inside. 
Jeremy, Konrad?

Thanks,

	Ingo

  parent reply	other threads:[~2011-12-16  8:55 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-16  8:19 [PATCH] x86: Use -m-omit-leaf-frame-pointer to shrink text size Ingo Molnar
2011-12-16  8:48 ` Andrew Morton
2011-12-16  8:54   ` Ingo Molnar
2011-12-16  8:53 ` Ingo Molnar [this message]
2011-12-16  9:23   ` Jeremy Fitzhardinge
2011-12-16 10:20     ` Peter Zijlstra
2011-12-16 16:27       ` Richard Henderson
2011-12-16 11:46     ` Jan Beulich
2011-12-16 12:00       ` Ingo Molnar
2011-12-16 15:32         ` H. Peter Anvin
2011-12-16 14:01 ` Frederic Weisbecker
2011-12-16 14:06 ` Frederic Weisbecker

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