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From: David Miller <davem@davemloft.net>
To: rostedt@goodmis.org
Cc: proski@gnu.org, a.p.zijlstra@chello.nl, pq@iki.fi,
	linux-kernel@vger.kernel.org, srostedt@redhat.com,
	linuxppc-dev@ozlabs.org, sandmann@redhat.com, paulus@samba.org,
	mingo@elte.hu
Subject: Re: [PATCH 2/2] ftrace: support for PowerPC
Date: Wed, 14 May 2008 22:28:57 -0700 (PDT)	[thread overview]
Message-ID: <20080514.222857.246967279.davem@davemloft.net> (raw)
In-Reply-To: <20080515035918.896765954@goodmis.org>

From: Steven Rostedt <rostedt@goodmis.org>
Date: Wed, 14 May 2008 23:49:44 -0400

> +#ifdef CONFIG_FTRACE
> +#ifdef CONFIG_DYNAMIC_FTRACE
> +_GLOBAL(mcount)
> +_GLOBAL(_mcount)
> +	stwu	r1,-48(r1)
> +	stw	r3, 12(r1)
> +	stw	r4, 16(r1)
> +	stw	r5, 20(r1)
> +	stw	r6, 24(r1)
> +	mflr	r3
> +	stw	r7, 28(r1)
> +	mfcr	r5
> +	stw	r8, 32(r1)
> +	stw	r9, 36(r1)
> +	stw	r10,40(r1)
> +	stw	r3, 44(r1)
> +	stw	r5, 8(r1)

Yikes, that's really expensive.

Can't you do a tail call and let the function you end
up calling do all the callee-saved register pops onto
the stack?

That's what I did on sparc.

  reply	other threads:[~2008-05-15  5:29 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-05-15  3:49 [PATCH 0/2] ftrace ported to PPC Steven Rostedt
2008-05-15  3:49 ` [PATCH 1/2] ftrace ppc: add irqs_disabled_flags to ppc Steven Rostedt
2008-05-16 12:05   ` Ingo Molnar
2008-05-15  3:49 ` [PATCH 2/2] ftrace: support for PowerPC Steven Rostedt
2008-05-15  5:28   ` David Miller [this message]
2008-05-15 13:38     ` Steven Rostedt
2008-05-15 16:48     ` Scott Wood
2008-05-16 12:06   ` Ingo Molnar
2008-05-20 14:04   ` Michael Ellerman
2008-05-20 14:17     ` Benjamin Herrenschmidt
2008-05-20 14:51       ` Steven Rostedt
2008-05-20 14:32     ` Steven Rostedt
2008-05-22 18:31     ` [PATCH] ftrace: powerpc clean ups Steven Rostedt
2008-05-27 15:36       ` Thomas Gleixner
2008-06-02  2:15       ` Michael Ellerman
2008-05-15  4:40 ` [PATCH 0/2] ftrace ported to PPC Paul Mackerras
2008-05-16 12:05   ` Ingo Molnar

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