Patchwork [PULL,15/28] exec: reduce L2_PAGE_SIZE

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Submitter Michael S. Tsirkin
Date Dec. 11, 2013, 6:30 p.m.
Message ID <1386786509-29966-15-git-send-email-mst@redhat.com>
Download mbox | patch
Permalink /patch/300275/
State New
Headers show

Comments

Michael S. Tsirkin - Dec. 11, 2013, 6:30 p.m.
With the single exception of ppc with 16M pages,
we get the same number of levels
with L2_PAGE_SIZE = 10 as with L2_PAGE_SIZE = 9.

by doing this we reduce memory footprint of a single level
in the node memory map by 2x without runtime overhead.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 exec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/exec.c b/exec.c
index f907f5f..67a073c 100644
--- a/exec.c
+++ b/exec.c
@@ -96,7 +96,7 @@  struct PhysPageEntry {
 /* Size of the L2 (and L3, etc) page tables.  */
 #define ADDR_SPACE_BITS 64
 
-#define P_L2_BITS 10
+#define P_L2_BITS 9
 #define P_L2_SIZE (1 << P_L2_BITS)
 
 #define P_L2_LEVELS (((ADDR_SPACE_BITS - TARGET_PAGE_BITS - 1) / P_L2_BITS) + 1)