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@xxxxxxxxxx>
--- 2010-04-30.orig/xen/arch/x86/domain_build.c 2010-05-04 10:30:34.000000000
+0200
+++ 2010-04-30/xen/arch/x86/domain_build.c 2010-05-04 10:31:32.000000000
+0200
@@ -126,26 +126,36 @@ string_param("dom0_ioports_disable", opt
static struct page_info * __init alloc_chunk(
struct domain *d, unsigned long max_pages)
{
+ static unsigned int __initdata last_order = MAX_ORDER;
+ static unsigned int __initdata memflags = MEMF_no_dma;
struct page_info *page;
- unsigned int order, free_order;
+ unsigned int order = get_order_from_pages(max_pages), free_order;
- /*
- * Allocate up to 2MB at a time: It prevents allocating very large chunks
- * from DMA pools before the >4GB pool is fully depleted.
- */
- if ( max_pages > (2UL << (20 - PAGE_SHIFT)) )
- max_pages = 2UL << (20 - PAGE_SHIFT);
- order = get_order_from_pages(max_pages);
- if ( (max_pages & (max_pages-1)) != 0 )
- order--;
- while ( (page = alloc_domheap_pages(d, order, 0)) == NULL )
+ if ( order > last_order )
+ order = last_order;
+ else if ( max_pages & (max_pages - 1) )
+ --order;
+ while ( (page = alloc_domheap_pages(d, order, memflags)) == NULL )
if ( order-- == 0 )
break;
+ if ( page )
+ last_order = order;
+ else if ( memflags )
+ {
+ /*
+ * Allocate up to 2MB at a time: It prevents allocating very large
+ * chunks from DMA pools before the >4GB pool is fully depleted.
+ */
+ last_order = 21 - PAGE_SHIFT;
+ memflags = 0;
+ return alloc_chunk(d, max_pages);
+ }
+
/*
* Make a reasonable attempt at finding a smaller chunk at a higher
* address, to avoid allocating from low memory as much as possible.
*/
- for ( free_order = order; page && order--; )
+ for ( free_order = order; !memflags && page && order--; )
{
struct page_info *pg2;
--- 2010-04-30.orig/xen/common/page_alloc.c 2010-05-04 10:30:34.000000000
+0200
+++ 2010-04-30/xen/common/page_alloc.c 2010-04-26 14:40:53.000000000 +0200
@@ -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) )
--- 2010-04-30.orig/xen/include/xen/mm.h 2010-05-04 10:30:34.000000000
+0200
+++ 2010-04-30/xen/include/xen/mm.h 2010-04-26 17:46:32.000000000 +0200
@@ -79,6 +79,8 @@ int assign_pages(
#define MEMF_populate_on_demand (1U<<_MEMF_populate_on_demand)
#define _MEMF_tmem 2
#define MEMF_tmem (1U<<_MEMF_tmem)
+#define _MEMF_no_dma 3
+#define MEMF_no_dma (1U<<_MEMF_no_dma)
#define _MEMF_node 8
#define MEMF_node(n) ((((n)+1)&0xff)<<_MEMF_node)
#define _MEMF_bits 24
x86-dom0-alloc-performance.patch
Description: Text document
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