Thanks Dajie:)
With 22 PGDIR_SHIFT, 15 extra page tables is populated when a whole 64M
address space is accessed, the patch can save memory quite a bit:)
Dajie Tan wrote:
32-bit Kernel for loongson2e currently use 16KB page size to avoid
cache alias problem.So, the definiton of PGDIR_SHIFT muse be 12+14.
Using 22 in 16K page size do not lead to a serious problem but the number
of pages allocated for page table is more than previous. (cat
/proc/vmstat | grep nr_page_table_pages)
It's been tested on FuLong mini PC(loongson2e inside).
Signed-off-by: Dajie Tan <jiankemeng@xxxxxxxxx>
---
include/asm-mips/pgtable-32.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/include/asm-mips/pgtable-32.h b/include/asm-mips/pgtable-32.h
index 2fbd47e..8d34ebf 100644
--- a/include/asm-mips/pgtable-32.h
+++ b/include/asm-mips/pgtable-32.h
@@ -46,7 +46,7 @@ extern int add_temporary_entry(unsigned long entrylo0, unsigned long entrylo1,
#ifdef CONFIG_64BIT_PHYS_ADDR
#define PGDIR_SHIFT 21
#else
-#define PGDIR_SHIFT 22
+#define PGDIR_SHIFT (PAGE_SHIFT + (PAGE_SHIFT + PTE_ORDER - 2))
#endif
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE-1))
