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Make I/O schedulers optional

PATCH In review Bernardo Innocenti 2 participants 3 messages Jul 27, 2003 Block layer

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Bernardo Innocenti

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PATCH 1/1 Make I/O schedulers optional

Hello Linus,

please apply this one. It has been reviewed and approved by both Jens Axboe and Andrew Morton.

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Add kconfig options to allow excluding either or both the I/O schedulers. Mostly useful for embedded systems (save ~13KB):

With my desktop PC (i386) kernel:

   text    data     bss     dec     hex filename
   2210707  475856  150444 2837007  2b4a0f vmlinux_with_ioscheds
   2197763  473446  150380 2821589  2b0dd5 vmlinux_without_ioscheds

With my uClinux (m68knommu) kernel:

   text    data     bss     dec     hex filename
   807760   47384   78884  934028   e408c linux_without_ioscheds
   819276   52460   78896  950632   e8168 linux_with_ioscheds
drivers/block/Kconfig.iosched +8 -0
diff -Nru linux-2.6.0-test1.orig/drivers/block/Kconfig.iosched linux-2.6.0-test1-with_elevator_patch/drivers/block/Kconfig.iosched
@@ -0,0 +1,8 @@
+config IOSCHED_AS
+	bool "Anticipatory I/O scheduler" if EMBEDDED
+	default y
+
+config IOSCHED_DEADLINE
+	bool "Deadline I/O scheduler" if EMBEDDED
+	default y
+
drivers/block/Makefile +3 -2
diff -Nru linux-2.6.0-test1.orig/drivers/block/Makefile linux-2.6.0-test1-with_elevator_patch/drivers/block/Makefile
@@ -13,9 +13,10 @@
 # kblockd threads
 #
 
-obj-y	:= elevator.o ll_rw_blk.o ioctl.o genhd.o scsi_ioctl.o \
-	deadline-iosched.o as-iosched.o
+obj-y	:= elevator.o ll_rw_blk.o ioctl.o genhd.o scsi_ioctl.o
 
+obj-$(CONFIG_IOSCHED_AS)	+= as-iosched.o
+obj-$(CONFIG_IOSCHED_DEADLINE)	+= deadline-iosched.o
 obj-$(CONFIG_MAC_FLOPPY)	+= swim3.o
 obj-$(CONFIG_BLK_DEV_FD)	+= floppy.o
 obj-$(CONFIG_BLK_DEV_FD98)	+= floppy98.o
drivers/block/as-iosched.c +1 -0
diff -Nru linux-2.6.0-test1.orig/drivers/block/as-iosched.c linux-2.6.0-test1-with_elevator_patch/drivers/block/as-iosched.c
@@ -1832,6 +1832,7 @@
 	.elevator_exit_fn =		as_exit,
 
 	.elevator_ktype =		&as_ktype,
+	.elevator_name =		"anticipatory scheduling",
 };
 
 EXPORT_SYMBOL(iosched_as);
drivers/block/deadline-iosched.c +1 -0
diff -Nru linux-2.6.0-test1.orig/drivers/block/deadline-iosched.c linux-2.6.0-test1-with_elevator_patch/drivers/block/deadline-iosched.c
@@ -941,6 +941,7 @@
 	.elevator_exit_fn =		deadline_exit,
 
 	.elevator_ktype =		&deadline_ktype,
+	.elevator_name =		"deadline",
 };
 
 EXPORT_SYMBOL(iosched_deadline);
drivers/block/elevator.c +1 -0
diff -Nru linux-2.6.0-test1.orig/drivers/block/elevator.c linux-2.6.0-test1-with_elevator_patch/drivers/block/elevator.c
@@ -409,6 +409,7 @@
 	.elevator_merge_req_fn		= elevator_noop_merge_requests,
 	.elevator_next_req_fn		= elevator_noop_next_request,
 	.elevator_add_req_fn		= elevator_noop_add_request,
+	.elevator_name			= "noop",
 };
 
 module_init(elevator_global_init);
drivers/block/ll_rw_blk.c +16 -5
diff -Nru linux-2.6.0-test1.orig/drivers/block/ll_rw_blk.c linux-2.6.0-test1-with_elevator_patch/drivers/block/ll_rw_blk.c
@@ -1205,17 +1205,31 @@
 
 static int __make_request(request_queue_t *, struct bio *);
 
-static elevator_t *chosen_elevator = &iosched_as;
+static elevator_t *chosen_elevator =
+#if defined(CONFIG_IOSCHED_AS)
+	&iosched_as;
+#elif defined(CONFIG_IOSCHED_DEADLINE)
+	&iosched_deadline;
+#else
+	&elevator_noop;
+#endif
 
+#if defined(CONFIG_IOSCHED_AS) || defined(CONFIG_IOSCHED_DEADLINE)
 static int __init elevator_setup(char *str)
 {
+#ifdef CONFIG_IOSCHED_DEADLINE
 	if (!strcmp(str, "deadline"))
 		chosen_elevator = &iosched_deadline;
+#endif
+#ifdef CONFIG_IOSCHED_AS
 	if (!strcmp(str, "as"))
 		chosen_elevator = &iosched_as;
+#endif
 	return 1;
 }
+
 __setup("elevator=", elevator_setup);
+#endif /* CONFIG_IOSCHED_AS || CONFIG_IOSCHED_DEADLINE */
 
 /**
  * blk_init_queue  - prepare a request queue for use with a block device

@@ -1255,10 +1269,7 @@
 
 	if (!printed) {
 		printed = 1;
-		if (chosen_elevator == &iosched_deadline)
-			printk("deadline elevator\n");
-		else if (chosen_elevator == &iosched_as)
-			printk("anticipatory scheduling elevator\n");
+		printk("Using %s elevator\n", chosen_elevator->elevator_name);
 	}
 
 	if ((ret = elevator_init(q, chosen_elevator))) {
init/Kconfig +2 -0
diff -Nru linux-2.6.0-test1.orig/init/Kconfig linux-2.6.0-test1-with_elevator_patch/init/Kconfig
@@ -141,6 +141,8 @@
 	  Disabling this option will cause the kernel to be built without
 	  support for epoll family of system calls.
 
+source "drivers/block/Kconfig.iosched"
+
 endmenu		# General setup
include/linux/elevator.h +1 -0
diff -Nru linux-2.6.0-test1.orig/include/linux/elevator.h linux-2.6.0-test1/include/linux/elevator.h
@@ -52,6 +52,7 @@
 
 	struct kobject kobj;
 	struct kobj_type *elevator_ktype;
+	const char *elevator_name;
 };
 
 /*
Signature · 4 lines
  // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/

Please don't send Word attachments - http://www.gnu.org/philosophy/no-word-attachments.html
#1 lore raw

drivers/block/Kconfig.iosched line 7

Quoted 9 lines

[[email protected]]

drivers/block/Kconfig.iosched +7 -0
+config IOSCHED_AS
+	bool "Anticipatory I/O scheduler" if EMBEDDED
+	default y
+
+config IOSCHED_DEADLINE
+	bool "Deadline I/O scheduler" if EMBEDDED
+	default y

Please provide the help entries too.

Signature · 1 line
Tomas Szepe <[email protected]>
author
#2 lore raw
Quoted 11 lines · Tomas Szepe

drivers/block/Kconfig.iosched line 7

Quoted 9 lines

[[email protected]]

drivers/block/Kconfig.iosched +7 -0
+config IOSCHED_AS
+	bool "Anticipatory I/O scheduler" if EMBEDDED
+	default y
+
+config IOSCHED_DEADLINE
+	bool "Deadline I/O scheduler" if EMBEDDED
+	default y

Please provide the help entries too.

I wanted to, and I looked for something in the documentation to cut & paste instead of making up an inaccurate description myself.

Unfortunately, the documentation wrote by Jens got lost in -mm.

Signature · 4 lines
  // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/

Please don't send Word attachments - http://www.gnu.org/philosophy/no-word-attachments.html