>
> 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 <asm/arch/irq.h>
>
> 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 <asm/ibm4xx.h>
>
> 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;
>
> /*
-
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