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Date: Thu, 13 May 2010 10:48:27 -0500
From: "Steven J. Magnani" <steve@...idescorp.com>
To: microblaze-uclinux@...e.uq.edu.au
Cc: monstr@...str.eu, linux-kernel@...r.kernel.org,
"Steven J. Magnani" <steve@...idescorp.com>
Subject: [PATCH][noMMU] microblaze: allow PAGE_SIZE configuration
Allow developer to configure memory page size at compile time.
Larger pages can improve performance on some workloads.
Based on PowerPC code.
Signed-off-by: Steven J. Magnani <steve@...idescorp.com>
---
diff -uprN a/arch/microblaze/include/asm/page.h b/arch/microblaze/include/asm/page.h
--- a/arch/microblaze/include/asm/page.h 2010-05-13 09:55:59.000000000 -0500
+++ b/arch/microblaze/include/asm/page.h 2010-05-13 10:39:51.000000000 -0500
@@ -23,8 +23,16 @@
#ifdef __KERNEL__
/* PAGE_SHIFT determines the page size */
-#define PAGE_SHIFT (12)
-#define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
+#if defined(CONFIG_MICROBLAZE_32K_PAGES)
+#define PAGE_SHIFT 15
+#elif defined(CONFIG_MICROBLAZE_16K_PAGES)
+#define PAGE_SHIFT 14
+#elif defined(CONFIG_MICROBLAZE_8K_PAGES)
+#define PAGE_SHIFT 13
+#else
+#define PAGE_SHIFT 12
+#endif
+#define PAGE_SIZE (ASM_CONST(1) << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
#define LOAD_OFFSET ASM_CONST((CONFIG_KERNEL_START-CONFIG_KERNEL_BASE_ADDR))
diff -uprN a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
--- a/arch/microblaze/Kconfig 2010-05-13 09:55:59.000000000 -0500
+++ b/arch/microblaze/Kconfig 2010-05-13 10:39:16.000000000 -0500
@@ -223,6 +223,36 @@ config TASK_SIZE
hex "Size of user task space" if TASK_SIZE_BOOL
default "0x80000000"
+choice
+ prompt "Page size"
+ default MICROBLAZE_4K_PAGES
+ depends on ADVANCED_OPTIONS
+ help
+ Select the kernel logical page size. Increasing the page size
+ will reduce software overhead at each page boundary, allow
+ hardware prefetch mechanisms to be more effective, and allow
+ larger dma transfers increasing IO efficiency and reducing
+ overhead. However the utilization of memory will increase.
+ For example, each cached file will using a multiple of the
+ page size to hold its contents and the difference between the
+ end of file and the end of page is wasted.
+
+ If unsure, choose 4K_PAGES.
+
+config MICROBLAZE_4K_PAGES
+ bool "4k page size"
+
+config MICROBLAZE_8K_PAGES
+ bool "8k page size" if !MMU
+
+config MICROBLAZE_16K_PAGES
+ bool "16k page size" if !MMU
+
+config MICROBLAZE_32K_PAGES
+ bool "32k page size" if !MMU
+
+endchoice
+
endmenu
source "mm/Kconfig"
diff -uprN a/arch/microblaze/kernel/cpu/mb.c b/arch/microblaze/kernel/cpu/mb.c
--- a/arch/microblaze/kernel/cpu/mb.c 2010-05-13 09:55:59.000000000 -0500
+++ b/arch/microblaze/kernel/cpu/mb.c 2010-05-13 10:40:38.000000000 -0500
@@ -126,6 +126,7 @@ static int show_cpuinfo(struct seq_file
cpuinfo.pvr_user1,
cpuinfo.pvr_user2);
+ count += seq_printf(m, "Page size:\t%lu\n", PAGE_SIZE);
return 0;
}
diff -uprN a/arch/microblaze/kernel/vmlinux.lds.S b/arch/microblaze/kernel/vmlinux.lds.S
--- a/arch/microblaze/kernel/vmlinux.lds.S 2010-05-13 09:55:59.000000000 -0500
+++ b/arch/microblaze/kernel/vmlinux.lds.S 2010-05-10 15:32:30.000000000 -0500
@@ -55,7 +55,7 @@ SECTIONS {
*/
.sdata2 : AT(ADDR(.sdata2) - LOAD_OFFSET) {
_ssrw = .;
- . = ALIGN(4096); /* page aligned when MMU used - origin 0x8 */
+ . = ALIGN(PAGE_SIZE); /* page aligned when MMU used */
*(.sdata2)
. = ALIGN(8);
_essrw = .;
@@ -70,7 +70,7 @@ SECTIONS {
/* Reserve some low RAM for r0 based memory references */
. = ALIGN(0x4) ;
r0_ram = . ;
- . = . + 4096; /* a page should be enough */
+ . = . + PAGE_SIZE; /* a page should be enough */
/* Under the microblaze ABI, .sdata and .sbss must be contiguous */
. = ALIGN(8);
@@ -120,7 +120,7 @@ SECTIONS {
__init_end_before_initramfs = .;
- .init.ramfs ALIGN(4096) : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
+ .init.ramfs ALIGN(PAGE_SIZE) : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
__initramfs_start = .;
*(.init.ramfs)
__initramfs_end = .;
@@ -132,11 +132,11 @@ SECTIONS {
* so that __init_end == __bss_start. This will make image.elf
* consistent with the image.bin
*/
- /* . = ALIGN(4096); */
+ /* . = ALIGN(PAGE_SIZE); */
}
__init_end = .;
- .bss ALIGN (4096) : AT(ADDR(.bss) - LOAD_OFFSET) {
+ .bss ALIGN (PAGE_SIZE) : AT(ADDR(.bss) - LOAD_OFFSET) {
/* page aligned when MMU used */
__bss_start = . ;
*(.bss*)
@@ -145,7 +145,7 @@ SECTIONS {
__bss_stop = . ;
_ebss = . ;
}
- . = ALIGN(4096);
+ . = ALIGN(PAGE_SIZE);
_end = .;
DISCARDS
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