Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
On Mon, 8 Aug 2005, Alexander Nyberg wrote: > > 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? I doubt you'd be able to collect convincing benchmark data, but skipping a branch (possibly mispredicted) is worth it IMO. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
On Mon, 8 Aug 2005, Alexander Nyberg wrote: 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? I doubt you'd be able to collect convincing benchmark data, but skipping a branch (possibly mispredicted) is worth it IMO. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
Karsten Wiese wrote: Am Montag, 8. August 2005 13:19 schrieb Alexander Nyberg: 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? Performance gain is small, but measurable: 0,02% Tested on an Atlon64 running at 1000MHz. I took this value from 9 runs (each with/without the patch) of $ time lame x.wav where each took about 1 minute. 3000 Interrupts/s were generated at the time by running $ jackd -R -dalsa -p64 -n2 0,02% really isn't that muchbut Athlon64 is better than P4 with branch predictions, I think. Erm... ok, I won't insist on having this patch applied ;-) Karsten Removing dead code is always good - 0.02% is small, but if 100 kernel developers all did the same, that adds up to 2% rather quickly, and that is nothing to sneeze at. I like your patch, but you should add some comments for maintainability about what CHECK_IRQ_PER_CPU does - see include/asm-generic/pgtable.h for similar styling. If also probably doesn't hurt to leave IRQ_PER_CPU defined even when ARCH_HAS_CHECK_IRQ_PER_CPU is not, since it looks cleaner and prevents future collisions with bits defined inside of an #ifdef. Zach - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
Am Montag, 8. August 2005 13:19 schrieb Alexander Nyberg: > > 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? Performance gain is small, but measurable: 0,02% Tested on an Atlon64 running at 1000MHz. I took this value from 9 runs (each with/without the patch) of $ time lame x.wav where each took about 1 minute. 3000 Interrupts/s were generated at the time by running $ jackd -R -dalsa -p64 -n2 0,02% really isn't that muchbut Athlon64 is better than P4 with branch predictions, I think. Erm... ok, I won't insist on having this patch applied ;-) Karsten ___ Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
>
> 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 11:46:10.0
> +0200
> +++ linux-2.6.13/include/asm-cris/irq.h 2005-08-08 11:41:12.0
> +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 08:38:33.0
> +0100
> +++ linux-2.6.13/include/asm-ia64/irq.h 2005-08-06 18:06:53.0
> +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 11:45:26.0
> +0200
> +++ linux-2.6.13/include/asm-parisc/irq.h 2005-08-06 18:05:22.0
> +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.h2005-08-08 11:46:10.0
> +0200
> +++ linux-2.6.13/include/asm-ppc/irq.h2005-08-08 11:41:14.0
> +0200
> @@ -19,6 +19,11 @@
> #define IRQ_POLARITY_POSITIVE0x2 /* high level or low->high edge
> */
> #define IRQ_POLARITY_NEGATIVE0x0 /* 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 08:38:33.0
> +0100
> +++ linux-2.6.13/include/asm-ppc64/irq.h 2005-08-06 18:06:58.0
> +0200
> @@ -33,6 +33,11 @@
> #define IRQ_POLARITY_POSITIVE0x2 /* high level or low->high edge
> */
> #define IRQ_POLARITY_NEGATIVE0x0 /* 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) (_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 11:46:10.0
> +0200
> +++ linux-2.6.13/include/linux/irq.h 2005-08-08 11:55:11.0 +0200
> @@ -32,7 +32,12 @@
> #define IRQ_WAITING 32 /* IRQ not yet seen - for autodetection */
> #define IRQ_LEVEL64 /* 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 11:46:11.0
> +0200
> +++ linux-2.6.13/kernel/irq/handle.c 2005-08-08 11:53:00.0 +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;
>
> /*
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at
Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
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 11:46:10.0
+0200
+++ linux-2.6.13/include/asm-cris/irq.h 2005-08-08 11:41:12.0
+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 08:38:33.0
+0100
+++ linux-2.6.13/include/asm-ia64/irq.h 2005-08-06 18:06:53.0
+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 11:45:26.0
+0200
+++ linux-2.6.13/include/asm-parisc/irq.h 2005-08-06 18:05:22.0
+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.h2005-08-08 11:46:10.0
+0200
+++ linux-2.6.13/include/asm-ppc/irq.h2005-08-08 11:41:14.0
+0200
@@ -19,6 +19,11 @@
#define IRQ_POLARITY_POSITIVE0x2 /* high level or low-high edge
*/
#define IRQ_POLARITY_NEGATIVE0x0 /* 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 08:38:33.0
+0100
+++ linux-2.6.13/include/asm-ppc64/irq.h 2005-08-06 18:06:58.0
+0200
@@ -33,6 +33,11 @@
#define IRQ_POLARITY_POSITIVE0x2 /* high level or low-high edge
*/
#define IRQ_POLARITY_NEGATIVE0x0 /* 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 11:46:10.0
+0200
+++ linux-2.6.13/include/linux/irq.h 2005-08-08 11:55:11.0 +0200
@@ -32,7 +32,12 @@
#define IRQ_WAITING 32 /* IRQ not yet seen - for autodetection */
#define IRQ_LEVEL64 /* 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 11:46:11.0
+0200
+++ linux-2.6.13/kernel/irq/handle.c 2005-08-08 11:53:00.0 +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;
/*
-
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
Am Montag, 8. August 2005 13:19 schrieb Alexander Nyberg: 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? Performance gain is small, but measurable: 0,02% Tested on an Atlon64 running at 1000MHz. I took this value from 9 runs (each with/without the patch) of $ time lame x.wav where each took about 1 minute. 3000 Interrupts/s were generated at the time by running $ jackd -R -dalsa -p64 -n2 0,02% really isn't that muchbut Athlon64 is better than P4 with branch predictions, I think. Erm... ok, I won't insist on having this patch applied ;-) Karsten ___ Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] CHECK_IRQ_PER_CPU() to avoid dead code in __do_IRQ()
Karsten Wiese wrote: Am Montag, 8. August 2005 13:19 schrieb Alexander Nyberg: 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? Performance gain is small, but measurable: 0,02% Tested on an Atlon64 running at 1000MHz. I took this value from 9 runs (each with/without the patch) of $ time lame x.wav where each took about 1 minute. 3000 Interrupts/s were generated at the time by running $ jackd -R -dalsa -p64 -n2 0,02% really isn't that muchbut Athlon64 is better than P4 with branch predictions, I think. Erm... ok, I won't insist on having this patch applied ;-) Karsten Removing dead code is always good - 0.02% is small, but if 100 kernel developers all did the same, that adds up to 2% rather quickly, and that is nothing to sneeze at. I like your patch, but you should add some comments for maintainability about what CHECK_IRQ_PER_CPU does - see include/asm-generic/pgtable.h for similar styling. If also probably doesn't hurt to leave IRQ_PER_CPU defined even when ARCH_HAS_CHECK_IRQ_PER_CPU is not, since it looks cleaner and prevents future collisions with bits defined inside of an #ifdef. Zach - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
