From: Christian Borntraeger <[email protected]>
[patch 12/13] s390: add read_mostly optimization.
Add a read_mostly section and define __read_mostly to prevent cache
line pollution due to writes for mostly read variables. In addition
fix the incorrect alignment of the cache_line_aligned data section.
s390 has a cacheline size of 256 bytes.
Signed-off-by: Christian Borntraeger <[email protected]>
Signed-off-by: Martin Schwidefsky <[email protected]>
---
arch/s390/kernel/vmlinux.lds.S | 4 +++-
include/asm-s390/cache.h | 2 ++
2 files changed, 5 insertions(+), 1 deletion(-)
diff -urpN linux-2.6/arch/s390/kernel/vmlinux.lds.S linux-2.6-patched/arch/s390/kernel/vmlinux.lds.S
--- linux-2.6/arch/s390/kernel/vmlinux.lds.S 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/vmlinux.lds.S 2006-04-24 16:47:29.000000000 +0200
@@ -58,9 +58,11 @@ SECTIONS
. = ALIGN(4096);
.data.page_aligned : { *(.data.idt) }
- . = ALIGN(32);
+ . = ALIGN(256);
.data.cacheline_aligned : { *(.data.cacheline_aligned) }
+ . = ALIGN(256);
+ .data.read_mostly : { *(.data.read_mostly) }
_edata = .; /* End of data section */
. = ALIGN(8192); /* init_task */
diff -urpN linux-2.6/include/asm-s390/cache.h linux-2.6-patched/include/asm-s390/cache.h
--- linux-2.6/include/asm-s390/cache.h 2006-03-20 06:53:29.000000000 +0100
+++ linux-2.6-patched/include/asm-s390/cache.h 2006-04-24 16:47:29.000000000 +0200
@@ -16,4 +16,6 @@
#define ARCH_KMALLOC_MINALIGN 8
+#define __read_mostly __attribute__((__section__(".data.read_mostly")))
+
#endif
-
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