From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750756AbVHHLTl (ORCPT ); Mon, 8 Aug 2005 07:19:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750822AbVHHLTl (ORCPT ); Mon, 8 Aug 2005 07:19:41 -0400 Received: from mailfe06.swip.net ([212.247.154.161]:21225 "EHLO swip.net") by vger.kernel.org with ESMTP id S1750756AbVHHLTl (ORCPT ); Mon, 8 Aug 2005 07:19:41 -0400 X-T2-Posting-ID: jLUmkBjoqvly7NM6d2gdCg== Date: Mon, 8 Aug 2005 13:19:36 +0200 From: Alexander Nyberg To: Karsten Wiese Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ() Message-ID: <20050808111936.GA1393@localhost.localdomain> References: <200508081250.05673.annabellesgarden@yahoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200508081250.05673.annabellesgarden@yahoo.de> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > > IRQ_PER_CPU is not used by all architectures. > This patch introduces the macros > ARCH_HAS_IRQ_PER_CPU and CHECK_IRQ_PER_CPU() to avoid the generation of > dead code in __do_IRQ(). > > ARCH_HAS_IRQ_PER_CPU is defined by architectures using > IRQ_PER_CPU in their > include/asm_ARCH/irq.h > file. > > Through grepping the tree I found the following > architectures currently use IRQ_PER_CPU: > > cris, ia64, ppc, ppc64 and parisc. > There are many places where one could replace run-time tests with #ifdef's but it makes reading more difficult (and in longer terms maintainence). Have you benchmarked any workload that benefits from this? > > diff -upr linux-2.6.13-rc6/include/asm-cris/irq.h linux-2.6.13/include/asm-cris/irq.h > --- linux-2.6.13-rc6/include/asm-cris/irq.h 2005-08-08 11:46:10.000000000 +0200 > +++ linux-2.6.13/include/asm-cris/irq.h 2005-08-08 11:41:12.000000000 +0200 > @@ -1,6 +1,11 @@ > #ifndef _ASM_IRQ_H > #define _ASM_IRQ_H > > +/* > + * IRQ line status macro IRQ_PER_CPU is used > + */ > +#define ARCH_HAS_IRQ_PER_CPU > + > #include > > extern __inline__ int irq_canonicalize(int irq) > diff -upr linux-2.6.13-rc6/include/asm-ia64/irq.h linux-2.6.13/include/asm-ia64/irq.h > --- linux-2.6.13-rc6/include/asm-ia64/irq.h 2005-03-02 08:38:33.000000000 +0100 > +++ linux-2.6.13/include/asm-ia64/irq.h 2005-08-06 18:06:53.000000000 +0200 > @@ -14,6 +14,11 @@ > #define NR_IRQS 256 > #define NR_IRQ_VECTORS NR_IRQS > > +/* > + * IRQ line status macro IRQ_PER_CPU is used > + */ > +#define ARCH_HAS_IRQ_PER_CPU > + > static __inline__ int > irq_canonicalize (int irq) > { > diff -upr linux-2.6.13-rc6/include/asm-parisc/irq.h linux-2.6.13/include/asm-parisc/irq.h > --- linux-2.6.13-rc6/include/asm-parisc/irq.h 2005-08-08 11:45:26.000000000 +0200 > +++ linux-2.6.13/include/asm-parisc/irq.h 2005-08-06 18:05:22.000000000 +0200 > @@ -26,6 +26,11 @@ > > #define NR_IRQS (CPU_IRQ_MAX + 1) > > +/* > + * IRQ line status macro IRQ_PER_CPU is used > + */ > +#define ARCH_HAS_IRQ_PER_CPU > + > static __inline__ int irq_canonicalize(int irq) > { > return (irq == 2) ? 9 : irq; > diff -upr linux-2.6.13-rc6/include/asm-ppc/irq.h linux-2.6.13/include/asm-ppc/irq.h > --- linux-2.6.13-rc6/include/asm-ppc/irq.h 2005-08-08 11:46:10.000000000 +0200 > +++ linux-2.6.13/include/asm-ppc/irq.h 2005-08-08 11:41:14.000000000 +0200 > @@ -19,6 +19,11 @@ > #define IRQ_POLARITY_POSITIVE 0x2 /* high level or low->high edge */ > #define IRQ_POLARITY_NEGATIVE 0x0 /* low level or high->low edge */ > > +/* > + * IRQ line status macro IRQ_PER_CPU is used > + */ > +#define ARCH_HAS_IRQ_PER_CPU > + > #if defined(CONFIG_40x) > #include > > diff -upr linux-2.6.13-rc6/include/asm-ppc64/irq.h linux-2.6.13/include/asm-ppc64/irq.h > --- linux-2.6.13-rc6/include/asm-ppc64/irq.h 2005-03-02 08:38:33.000000000 +0100 > +++ linux-2.6.13/include/asm-ppc64/irq.h 2005-08-06 18:06:58.000000000 +0200 > @@ -33,6 +33,11 @@ > #define IRQ_POLARITY_POSITIVE 0x2 /* high level or low->high edge */ > #define IRQ_POLARITY_NEGATIVE 0x0 /* low level or high->low edge */ > > +/* > + * IRQ line status macro IRQ_PER_CPU is used > + */ > +#define ARCH_HAS_IRQ_PER_CPU > + > #define get_irq_desc(irq) (&irq_desc[(irq)]) > > /* Define a way to iterate across irqs. */ > diff -upr linux-2.6.13-rc6/include/linux/irq.h linux-2.6.13/include/linux/irq.h > --- linux-2.6.13-rc6/include/linux/irq.h 2005-08-08 11:46:10.000000000 +0200 > +++ linux-2.6.13/include/linux/irq.h 2005-08-08 11:55:11.000000000 +0200 > @@ -32,7 +32,12 @@ > #define IRQ_WAITING 32 /* IRQ not yet seen - for autodetection */ > #define IRQ_LEVEL 64 /* IRQ level triggered */ > #define IRQ_MASKED 128 /* IRQ masked - shouldn't be seen again */ > -#define IRQ_PER_CPU 256 /* IRQ is per CPU */ > +#if defined(ARCH_HAS_IRQ_PER_CPU) > +# define IRQ_PER_CPU 256 /* IRQ is per CPU */ > +# define CHECK_IRQ_PER_CPU(var) ((var) & IRQ_PER_CPU) > +#else > +# define CHECK_IRQ_PER_CPU(var) 0 > +#endif > > /* > * Interrupt controller descriptor. This is all we need > diff -upr linux-2.6.13-rc6/kernel/irq/handle.c linux-2.6.13/kernel/irq/handle.c > --- linux-2.6.13-rc6/kernel/irq/handle.c 2005-08-08 11:46:11.000000000 +0200 > +++ linux-2.6.13/kernel/irq/handle.c 2005-08-08 11:53:00.000000000 +0200 > @@ -111,7 +111,7 @@ fastcall unsigned int __do_IRQ(unsigned > unsigned int status; > > kstat_this_cpu.irqs[irq]++; > - if (desc->status & IRQ_PER_CPU) { > + if (CHECK_IRQ_PER_CPU(desc->status)) { > irqreturn_t action_ret; > > /*