Re: HZ, preferably as small as possible

[Thunder from the hill]

Hi,

On Wed, 10 Jul 2002, Thunder from the hill wrote:
> I guess I forgot the half of it...

I did. Here is the whole version:

Index: arch/i386/Config.help
===================================================================
RCS file: /var/cvs/thunder-2.5/arch/i386/Config.help,v
retrieving revision 1.4
diff -p -u -r1.4 Config.help
--- arch/i386/Config.help	7 Jul 2002 09:59:46 -0000	1.4
+++ arch/i386/Config.help	10 Jul 2002 22:40:17 -0000
@@ -991,3 +991,13 @@ CONFIG_X86_EARLY_PRINTK
   to the console  much earlier in the boot  process than printk.  This
   is useful when  debugging fatal problems early in  the boot sequence
   (e.g. within setup_arch).  If unsure, say N.
+
+Low kernel scheduler rate
+CONFIG_SCHED_LOW_HZ
+  Enable this  if you care about  your CPU sleeping  time. The current
+  interval for  scheduling processes in  the kernel has  recently been
+  increased. The advantage is less latency for many things that depend
+  on the  timer, the disadvantage is  that your cpu  will probably not
+  go to sleep in time (so  CPU power management will possibly not work
+  at all)
+
Index: include/asm-i386/param.h
===================================================================
RCS file: /var/cvs/thunder-2.5/include/asm-i386/param.h,v
retrieving revision 1.2
diff -p -u -r1.2 param.h
--- include/asm-i386/param.h	6 Jul 2002 18:17:30 -0000	1.2
+++ include/asm-i386/param.h	10 Jul 2002 22:40:17 -0000
@@ -2,7 +2,11 @@
 #define _ASMi386_PARAM_H
 
 #ifdef __KERNEL__
-# define HZ		1000		/* Internal kernel timer frequency */
+# ifdef CONFIG_SCHED_LOW_HZ
+#  define HZ		100		/* Internal kernel timer frequency */
+# else
+#  define HZ		1000		/* Internal kernel timer frequency */
+# endif
 # define USER_HZ	100		/* .. some user interfaces are in "ticks" */
 # define CLOCKS_PER_SEC	(USER_HZ)	/* like times() */
 #endif
Index: arch/i386/config.in
===================================================================
RCS file: /var/cvs/thunder-2.5/arch/i386/config.in,v
retrieving revision 1.8
diff -p -u -r1.8 config.in
--- arch/i386/config.in	7 Jul 2002 09:59:47 -0000	1.8
+++ arch/i386/config.in	10 Jul 2002 22:45:28 -0000
@@ -181,6 +181,7 @@ else
    bool 'Multiquad NUMA system' CONFIG_MULTIQUAD
 fi
 
+bool 'Low scheduler rates' CONFIG_SCHED_LOW_HZ
 bool 'Machine Check Exception' CONFIG_X86_MCE
 dep_bool 'Check for non-fatal errors on Athlon/Duron' CONFIG_X86_MCE_NONFATAL $CONFIG_X86_MCE
 dep_bool 'check for P4 thermal throttling interrupt.' CONFIG_X86_MCE_P4THERMAL $CONFIG_X86_MCE $CONFIG_X86_UP_APIC

							Regards,
							Thunder
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