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Commit 59121003 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

[PATCH] i386: Selectable Frequency of the Timer Interrupt 



Make the timer frequency selectable. The timer interrupt may cause bus
and memory contention in large NUMA systems since the interrupt occurs
on each processor HZ times per second.

Signed-off-by: default avatarChristoph Lameter <christoph@lameter.com>
Signed-off-by: default avatarShai Fultheim <shai@scalex86.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 799d19f6

arch/i386/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -961,6 +961,8 @@ config SECCOMP 


	  If unsure, say Y. Only embedded should say N here.



source kernel/Kconfig.hz



endmenu

arch/x86_64/Kconfig

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Original line number Diff line number Diff line
@@ -402,6 +402,8 @@ config SECCOMP 


	  If unsure, say Y. Only embedded should say N here.



source kernel/Kconfig.hz



endmenu



#

include/asm-i386/param.h

+3 −1
Original line number Diff line number Diff line 
#include <linux/config.h>



#ifndef _ASMi386_PARAM_H

#define _ASMi386_PARAM_H



#ifdef __KERNEL__

# define HZ		1000		/* Internal kernel timer frequency */

# define HZ		CONFIG_HZ	/* Internal kernel timer frequency */

# define USER_HZ	100		/* .. some user interfaces are in "ticks" */

# define CLOCKS_PER_SEC		(USER_HZ)	/* like times() */

#endif

include/asm-x86_64/param.h

+4 −2
Original line number Diff line number Diff line 
#include <linux/config.h>



#ifndef _ASMx86_64_PARAM_H

#define _ASMx86_64_PARAM_H



#ifdef __KERNEL__

# define HZ            1000            /* Internal kernel timer frequency */

# define HZ            CONFIG_HZ	/* Internal kernel timer frequency */

# define USER_HZ       100		/* .. some user interfaces are in "ticks */

#define CLOCKS_PER_SEC        (USER_HZ)       /* like times() */

#endif

kernel/Kconfig.hz

0 → 100644
+46 −0
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#

# Timer Interrupt Frequency Configuration

#



choice

	prompt "Timer frequency"

	default HZ_250

	help

	 Allows the configuration of the timer frequency. It is customary

	 to have the timer interrupt run at 1000 HZ but 100 HZ may be more

	 beneficial for servers and NUMA systems that do not need to have

	 a fast response for user interaction and that may experience bus

	 contention and cacheline bounces as a result of timer interrupts.

	 Note that the timer interrupt occurs on each processor in an SMP

	 environment leading to NR_CPUS * HZ number of timer interrupts

	 per second.





	config HZ_100

		bool "100 HZ"

	help

	  100 HZ is a typical choice for servers, SMP and NUMA systems

	  with lots of processors that may show reduced performance if

	  too many timer interrupts are occurring.



	config HZ_250

		bool "250 HZ"

	help

	 250 HZ is a good compromise choice allowing server performance

	 while also showing good interactive responsiveness even

	 on SMP and NUMA systems.



	config HZ_1000

		bool "1000 HZ"

	help

	 1000 HZ is the preferred choice for desktop systems and other

	 systems requiring fast interactive responses to events.



endchoice



config HZ

	int

	default 100 if HZ_100

	default 250 if HZ_250

	default 1000 if HZ_1000