In the function __nr_to_section,
Use shift operation instead of division operation
in order to improve the performance of memory management.
There are no functional changes.
Some performance data is as follows:
Machine configuration: Hygon 128 cores, 256M memory
Stream single core:
with patch without patch promote
Copy 23376.7731 23907.1532 -1.27%
Scale 12580.2913 11679.7852 +7.71%
Add 11922.9562 11461.8669 +4.02%
Triad 12549.2735 11491.9798 +9.20%
Signed-off-by: Guo Hui <guohui@xxxxxxxxxxxxx>
---
include/linux/mmzone.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 5e50b78d58ea..8dde6fb56109 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1818,7 +1818,8 @@ struct mem_section {
#define SECTIONS_PER_ROOT 1
#endif
-#define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
+#define SECTION_ROOT_SHIFT (__builtin_popcount(SECTIONS_PER_ROOT - 1))
+#define SECTION_NR_TO_ROOT(sec) ((sec) >> SECTION_ROOT_SHIFT)
#define NR_SECTION_ROOTS DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
#define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)
--
2.20.1
