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From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
To: vagabon.xyz@gmail.com
Cc: ralf@linux-mips.org, linux-mips@linux-mips.org
Subject: Re: [PATCH] clean up ret_from_{irq,exception}
Date: Sun, 11 Feb 2007 00:40:20 +0900 (JST)	[thread overview]
Message-ID: <20070211.004020.79071872.anemo@mba.ocn.ne.jp> (raw)
In-Reply-To: <45C8A477.8070906@innova-card.com>

On Tue, 06 Feb 2007 16:53:27 +0100, Franck Bui-Huu <vagabon.xyz@gmail.com> wrote:
> This patch makes these routines a lot more readable whatever
> the value of CONFIG_PREEMPT.
> 
> It also moves one branch instruction from ret_from_irq()
> to ret_from_exception(). Therefore we favour the return
> from irq path which should be more common than the other
> one.

After this patch, entry.S becomes:

FEXPORT(ret_from_exception)
#ifndef CONFIG_PREEMPT
	local_irq_disable			# preempt stop
#endif
	b	_ret_from_irq
FEXPORT(ret_from_irq)
	LONG_S	s0, TI_REGS($28)
FEXPORT(_ret_from_irq)


Apparently your patch add an additional branch in critical path in
CONFIG_PREEMPT=y case.

Maybe this would be better?

#ifdef CONFIG_PREEMPT
FEXPORT(ret_from_irq)
	LONG_S	s0, TI_REGS($28)
FEXPORT(ret_from_exception)
#else
FEXPORT(ret_from_exception)
	local_irq_disable			# preempt stop
	b	_ret_from_irq
FEXPORT(ret_from_irq)
	LONG_S	s0, TI_REGS($28)
#endif
FEXPORT(_ret_from_irq)

---
Atsushi Nemoto

  reply	other threads:[~2007-02-10 15:41 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-06 15:53 [PATCH] clean up ret_from_{irq,exception} Franck Bui-Huu
2007-02-10 15:40 ` Atsushi Nemoto [this message]
2007-02-12  8:44   ` Franck Bui-Huu
2007-02-12 14:45     ` Atsushi Nemoto
2007-02-12 15:55       ` Franck Bui-Huu
2007-02-12 16:51       ` Maciej W. Rozycki
2007-02-12 17:01         ` Atsushi Nemoto

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