kernel_optimize_test/arch/sh/kernel/vmlinux.lds.S
Fenghua Yu 5fb7dc37dc define new percpu interface for shared data
per cpu data section contains two types of data.  One set which is
exclusively accessed by the local cpu and the other set which is per cpu,
but also shared by remote cpus.  In the current kernel, these two sets are
not clearely separated out.  This can potentially cause the same data
cacheline shared between the two sets of data, which will result in
unnecessary bouncing of the cacheline between cpus.

One way to fix the problem is to cacheline align the remotely accessed per
cpu data, both at the beginning and at the end.  Because of the padding at
both ends, this will likely cause some memory wastage and also the
interface to achieve this is not clean.

This patch:

Moves the remotely accessed per cpu data (which is currently marked
as ____cacheline_aligned_in_smp) into a different section, where all the data
elements are cacheline aligned. And as such, this differentiates the local
only data and remotely accessed data cleanly.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:44 -07:00

125 lines
2.6 KiB
ArmAsm

/* $Id: vmlinux.lds.S,v 1.8 2003/05/16 17:18:14 lethal Exp $
* ld script to make SuperH Linux kernel
* Written by Niibe Yutaka
*/
#include <asm/thread_info.h>
#include <asm/cache.h>
#include <asm-generic/vmlinux.lds.h>
#ifdef CONFIG_CPU_LITTLE_ENDIAN
OUTPUT_FORMAT("elf32-sh-linux", "elf32-sh-linux", "elf32-sh-linux")
#else
OUTPUT_FORMAT("elf32-shbig-linux", "elf32-shbig-linux", "elf32-shbig-linux")
#endif
OUTPUT_ARCH(sh)
ENTRY(_start)
SECTIONS
{
. = CONFIG_PAGE_OFFSET + CONFIG_MEMORY_START + CONFIG_ZERO_PAGE_OFFSET;
_text = .; /* Text and read-only data */
text = .; /* Text and read-only data */
.empty_zero_page : {
*(.empty_zero_page)
} = 0
.text : {
TEXT_TEXT
SCHED_TEXT
LOCK_TEXT
*(.fixup)
*(.gnu.warning)
} = 0x0009
. = ALIGN(16); /* Exception table */
__start___ex_table = .;
__ex_table : { *(__ex_table) }
__stop___ex_table = .;
_etext = .; /* End of text section */
RODATA
BUG_TABLE
.data : { /* Data */
DATA_DATA
/* Align the initial ramdisk image (INITRD) on page boundaries. */
. = ALIGN(PAGE_SIZE);
__rd_start = .;
*(.initrd)
. = ALIGN(PAGE_SIZE);
__rd_end = .;
CONSTRUCTORS
}
. = ALIGN(PAGE_SIZE);
.data.page_aligned : { *(.data.page_aligned) }
__nosave_begin = .;
.data_nosave : { *(.data.nosave) }
. = ALIGN(PAGE_SIZE);
__nosave_end = .;
PERCPU(PAGE_SIZE)
.data.cacheline_aligned : { *(.data.cacheline_aligned) }
_edata = .; /* End of data section */
. = ALIGN(THREAD_SIZE); /* init_task */
.data.init_task : { *(.data.init_task) }
. = ALIGN(PAGE_SIZE); /* Init code and data */
__init_begin = .;
_sinittext = .;
.init.text : { *(.init.text) }
_einittext = .;
.init.data : { *(.init.data) }
. = ALIGN(16);
__setup_start = .;
.init.setup : { *(.init.setup) }
__setup_end = .;
__initcall_start = .;
.initcall.init : {
INITCALLS
}
__initcall_end = .;
__con_initcall_start = .;
.con_initcall.init : { *(.con_initcall.init) }
__con_initcall_end = .;
SECURITY_INIT
#ifdef CONFIG_BLK_DEV_INITRD
__initramfs_start = .;
.init.ramfs : { *(.init.ramfs) }
__initramfs_end = .;
#endif
. = ALIGN(4);
__machvec_start = .;
.machvec.init : { *(.machvec.init) }
__machvec_end = .;
. = ALIGN(PAGE_SIZE);
.bss : {
__init_end = .;
__bss_start = .; /* BSS */
*(.bss.page_aligned)
*(.bss)
. = ALIGN(4);
_end = . ;
}
/* When something in the kernel is NOT compiled as a module, the
* module cleanup code and data are put into these segments. Both
* can then be thrown away, as cleanup code is never called unless
* it's a module.
*/
/DISCARD/ : {
*(.exitcall.exit)
}
STABS_DEBUG
DWARF_DEBUG
}