[Xen-devel] [PATCH 2/2] try to put heap control structures on the target node

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

This also neatly eliminates (in certain cases) the need to reserve a
page between nodes, as the heap control structures will never be freed
and thus can serve as the needed separator.

It also adds an additonal fallback attempting to make use of the wasted
tail of a (group of) page(s) used for the _heap array by putting the
avail array there if it fits.

This patch will only apply cleanly on top of the struct page_info
modification patches sent earlier.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- 2009-01-30.orig/xen/common/page_alloc.c     2009-01-30 09:16:50.000000000 
+0100
+++ 2009-01-30/xen/common/page_alloc.c  2009-01-30 10:33:31.000000000 +0100
@@ -272,13 +272,16 @@ static unsigned long *avail[MAX_NUMNODES
 
 static DEFINE_SPINLOCK(heap_lock);
 
-static void init_node_heap(int node)
+static unsigned long init_node_heap(int node, unsigned long mfn,
+                                    unsigned long nr)
 {
     /* First node to be discovered has its heap metadata statically alloced. */
     static heap_by_zone_and_order_t _heap_static;
     static unsigned long avail_static[NR_ZONES];
     static int first_node_initialised;
-
+    unsigned long needed = (sizeof(**_heap) +
+                            sizeof(**avail) * NR_ZONES +
+                            PAGE_SIZE - 1) >> PAGE_SHIFT;
     int i, j;
 
     if ( !first_node_initialised )
@@ -286,12 +289,31 @@ static void init_node_heap(int node)
         _heap[node] = &_heap_static;
         avail[node] = avail_static;
         first_node_initialised = 1;
+        needed = 0;
+    }
+#ifdef DIRECTMAP_VIRT_END
+    else if ( nr >= needed &&
+              mfn + needed <= virt_to_mfn(DIRECTMAP_VIRT_END) )
+    {
+        _heap[node] = mfn_to_virt(mfn);
+        avail[node] = mfn_to_virt(mfn + needed) - sizeof(**avail) * NR_ZONES;
+    }
+#endif
+    else if ( get_order_from_bytes(sizeof(**_heap)) ==
+              get_order_from_pages(needed) )
+    {
+        _heap[node] = alloc_xenheap_pages(get_order_from_pages(needed), 0);
+        BUG_ON(!_heap[node]);
+        avail[node] = (void *)_heap[node] + (needed << PAGE_SHIFT) -
+                      sizeof(**avail) * NR_ZONES;
+        needed = 0;
     }
     else
     {
         _heap[node] = xmalloc(heap_by_zone_and_order_t);
         avail[node] = xmalloc_array(unsigned long, NR_ZONES);
         BUG_ON(!_heap[node] || !avail[node]);
+        needed = 0;
     }
 
     memset(avail[node], 0, NR_ZONES * sizeof(long));
@@ -299,6 +321,8 @@ static void init_node_heap(int node)
     for ( i = 0; i < NR_ZONES; i++ )
         for ( j = 0; j <= MAX_ORDER; j++ )
             INIT_PAGE_LIST_HEAD(&(*_heap[node])[i][j]);
+
+    return needed;
 }
 
 /* Allocate 2^@order contiguous pages. */
@@ -487,12 +511,22 @@ static void init_heap_pages(
 
     nid_prev = phys_to_nid(page_to_maddr(pg-1));
 
-    for ( i = 0; i < nr_pages; i++ )
+    for ( i = 0; i < nr_pages; nid_prev = nid_curr, i++ )
     {
         nid_curr = phys_to_nid(page_to_maddr(pg+i));
 
         if ( unlikely(!avail[nid_curr]) )
-            init_node_heap(nid_curr);
+        {
+            unsigned long n;
+
+            n = init_node_heap(nid_curr, page_to_mfn(pg+i), nr_pages - i);
+            if ( n )
+            {
+                BUG_ON(i + n > nr_pages);
+                i += n - 1;
+                continue;
+            }
+        }
 
         /*
          * Free pages of the same node, or if they differ, but are on a
@@ -504,8 +538,6 @@ static void init_heap_pages(
         else
             printk("Reserving non-aligned node boundary @ mfn %#lx\n",
                    page_to_mfn(pg+i));
-
-        nid_prev = nid_curr;
     }
 }
 
@@ -533,7 +565,7 @@ static unsigned long avail_heap_pages(
 #define avail_for_domheap(mfn) !(allocated_in_map(mfn) || is_xen_heap_mfn(mfn))
 void __init end_boot_allocator(void)
 {
-    unsigned long i;
+    unsigned long i, nr = 0;
     int curr_free, next_free;
 
     /* Pages that are free now go to the domain sub-allocator. */
@@ -546,8 +578,15 @@ void __init end_boot_allocator(void)
         if ( next_free )
             map_alloc(i+1, 1); /* prevent merging in free_heap_pages() */
         if ( curr_free )
-            init_heap_pages(mfn_to_page(i), 1);
+            ++nr;
+        else if ( nr )
+        {
+            init_heap_pages(mfn_to_page(i - nr), nr);
+            nr = 0;
+        }
     }
+    if ( nr )
+        init_heap_pages(mfn_to_page(i - nr), nr);
 
     if ( !dma_bitsize && (num_online_nodes() > 1) )
     {



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