[PATCH 2.6.14-rc1-git5] block-kconfig-iosched-default-selection.patch

[MichalK]

>From Michal Kaczmarski <fallow@xxxxxxxxxxxx>

I think selection of a default IO scheduler via Kconfig 
can be a nice addition to the kernel.
---
 Kconfig.iosched |   17 +++++++++++++++++
 elevator.c      |   35 ++++++++++++++++++++++++++---------
 2 files changed, 43 insertions(+), 9 deletions(-)

diff -Naur a/drivers/block/Kconfig.iosched b/drivers/block/Kconfig.iosched
--- a/drivers/block/Kconfig.iosched	2005-08-29 01:41:01.000000000 +0200
+++ b/drivers/block/Kconfig.iosched	2005-09-21 19:09:56.000000000 +0200
@@ -38,4 +38,21 @@
 	  among all processes in the system. It should provide a fair
 	  working environment, suitable for desktop systems.
 
+choice 
+	prompt "Default IO scheduler"
+	default IOSCHED_DEFAULT_AS
+	---help---
+	  This option gives you possibility of choice the default IO 
+	  scheduler from selected to compile IO schedulers.
+	  
+config	IOSCHED_DEFAULT_AS 
+	bool "Anticipatory IO scheduler" if IOSCHED_AS
+config	IOSCHED_DEFAULT_DEADLINE 
+	bool "Deadline IO scheduler" if IOSCHED_DEADLINE
+config	IOSCHED_DEFAULT_CFQ 
+	bool "CFQ IO scheduler" if IOSCHED_CFQ
+config	IOSCHED_DEFAULT_NOOP
+	bool "NOOP IO scheduler" if IOSCHED_NOOP
+endchoice
+
 endmenu
diff -Naur a/drivers/block/elevator.c b/drivers/block/elevator.c
--- a/drivers/block/elevator.c	2005-08-29 01:41:01.000000000 +0200
+++ b/drivers/block/elevator.c	2005-09-21 19:33:10.000000000 +0200
@@ -24,6 +24,7 @@
  * - completely modularize elevator setup and teardown
  *
  */
+#include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/blkdev.h>
@@ -153,21 +154,37 @@
 
 static void elevator_setup_default(void)
 {
-	/*
-	 * check if default is set and exists
-	 */
-	if (chosen_elevator[0] && elevator_find(chosen_elevator))
-		return;
 
 #if defined(CONFIG_IOSCHED_AS)
+ #if defined(CONFIG_IOSCHED_DEFAULT_AS)
 	strcpy(chosen_elevator, "anticipatory");
-#elif defined(CONFIG_IOSCHED_DEADLINE)
+ #endif
+#endif
+#if defined(CONFIG_IOSCHED_DEADLINE)
+ #if defined(CONFIG_IOSCHED_DEFAULT_DEADLINE)
 	strcpy(chosen_elevator, "deadline");
-#elif defined(CONFIG_IOSCHED_CFQ)
+ #endif
+#endif
+#if defined(CONFIG_IOSCHED_CFQ)
+ #if defined(CONFIG_IOSCHED_DEFAULT_CFQ)
 	strcpy(chosen_elevator, "cfq");
-#elif defined(CONFIG_IOSCHED_NOOP)
+ #endif
+#endif
+#if defined(CONFIG_IOSCHED_NOOP)
+ #if defined(CONFIG_IOSCHED_DEFAULT_NOOP)
 	strcpy(chosen_elevator, "noop");
-#else
+ #endif
+#endif
+
+	/*
+	 * check if default is set and exists
+	 */
+	if (chosen_elevator[0] && elevator_find(chosen_elevator))
+		return;
+	else strcpy(chosen_elevator, "noop");
+	
+	
+#if !defined(CONFIG_IOSCHED_AS) && !defined(CONFIG_IOSCHED_DEADLINE) && !defined(CONFIG_IOSCHED_CFQ) && !defined(CONFIG_IOSCHED_NOOP)
 #error "You must build at least 1 IO scheduler into the kernel"
 #endif
 }