[XEN] Reduce default maximum allocation order from 2^20 pages to 2^11.

On x86 this corresponds to a maximum aligned contiguous allocation of 8MB.
This can be overridden by architectures if need be.
Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 327758f2c22dbdc08ed657f34278105601bb1c57..e33fbc2e524795cdddbba6cd9a84e63c07a2c5fb 100644 (file)
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -68,8 +68,11 @@ unsigned long avail_domheap_pages(void);
 
 #define ALLOC_DOM_DMA 1
 
-/* Up to 2^20 pages can be allocated at once. */
-#define MAX_ORDER 20
+#ifdef CONFIG_PAGEALLOC_MAX_ORDER
+#define MAX_ORDER CONFIG_PAGEALLOC_MAX_ORDER
+#else
+#define MAX_ORDER 11 /* 2^11 contiguous pages */
+#endif
 
 /* Automatic page scrubbing for dead domains. */
 extern struct list_head page_scrub_list;