x86: fix Dom0 booting time regression

Unfortunately the changes in c/s 21035 caused boot time to go up
significantly on certain large systems. To rectify this without going
back to the old behavior, introduce a new memory allocation flag so
that Dom0 allocations can exhaust non-DMA memory before starting to
consume DMA memory. For the latter, the behavior introduced in
aforementioned c/s gets retained, while for the former we can now even
try larger chunks first.

This builds on the fact that alloc_chunk() gets called with non-
increasing 'max_pages' arguments, end hence it can store locally the
allocation order last used (as larger order allocations can't succeed
during subsequent invocations if they failed once).

Signed-off-by: Jan Beulich <jbeulich@novell.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 53437a461a..6a1b6bde72 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -1157,8 +1157,9 @@ struct page_info *alloc_domheap_pages(
         pg = alloc_heap_pages(dma_zone + 1, zone_hi, node, order, memflags);
 
     if ( (pg == NULL) &&
-         ((pg = alloc_heap_pages(MEMZONE_XEN + 1, zone_hi,
-                                 node, order, memflags)) == NULL) )
+         ((memflags & MEMF_no_dma) ||
+          ((pg = alloc_heap_pages(MEMZONE_XEN + 1, zone_hi,
+                                  node, order, memflags)) == NULL)) )
          return NULL;
 
     if ( (d != NULL) && assign_pages(d, pg, order, memflags) )