Introduce s390 specific page comparison and checksumming functions:
The s390-specific functions use the CKSM instruction to quickly
calculate the checksum of a page.
This provides a measurable reduction on CPU load when KSM is active.
Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/Kbuild | 1 -
arch/s390/include/asm/page_memops.h | 18 ++++++++++++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
create mode 100644 arch/s390/include/asm/page_memops.h
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index e68b429..b3c8847 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -14,7 +14,6 @@ generic-y += local.h
generic-y += local64.h
generic-y += mcs_spinlock.h
generic-y += mm-arch-hooks.h
-generic-y += page_memops.h
generic-y += preempt.h
generic-y += trace_clock.h
generic-y += word-at-a-time.h
diff --git a/arch/s390/include/asm/page_memops.h b/arch/s390/include/asm/page_memops.h
new file mode 100644
index 0000000..48b829b
--- /dev/null
+++ b/arch/s390/include/asm/page_memops.h
@@ -0,0 +1,18 @@
+#ifndef _ASM_S390_PAGE_MEMOPS_H
+#define _ASM_S390_PAGE_MEMOPS_H
+
+#include <linux/mm_types.h>
+#include <linux/highmem.h>
+#include <asm/checksum.h>
+
+static inline u32 calc_page_checksum(struct page *page)
+{
+ return csum_partial(page_address(page), PAGE_SIZE, 0);
+}
+
+static inline int memcmp_pages(struct page *page1, struct page *page2)
+{
+ return memcmp(page_address(page1), page_address(page2), PAGE_SIZE);
+}
+
+#endif
--
2.7.4
