[Xen-devel] [PATCH v2 2/3] xen: introduce function merge_free_trunks

[Bob Liu <lliubbo@xxxxxxxxx>]

Separated from free_heap_pages(), will be used by idle vcpu scrubbing.

Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
---
 xen/common/page_alloc.c |  118 +++++++++++++++++++++++++----------------------
 1 file changed, 64 insertions(+), 54 deletions(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index c184f86..ab293c8 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -831,11 +831,73 @@ static int reserve_offlined_page(struct page_info *head)
     return count;
 }
 
+static void merge_free_trunks(struct page_info *pg, unsigned int order,
+    unsigned int node, unsigned int zone, bool_t need_scrub)
+{
+    unsigned long mask;
+
+    ASSERT(spin_is_locked(&heap_lock));
+
+    /* Merge chunks as far as possible. */
+    while ( order < MAX_ORDER )
+    {
+        mask = 1UL << order;
+
+        if ( (page_to_mfn(pg) & mask) )
+        {
+            /* Merge with predecessor block? */
+            if ( !mfn_valid(page_to_mfn(pg-mask)) ||
+                 !page_state_is(pg-mask, free) ||
+                 (PFN_ORDER(pg-mask) != order) ||
+                 (phys_to_nid(page_to_maddr(pg-mask)) != node) )
+                break;
+            /* If we need scrub, only merge with PGC_need_scrub pages */
+            if ( need_scrub )
+            {
+                if ( !test_bit(_PGC_need_scrub, &(pg-mask)->count_info) )
+                    break;
+            }
+            else
+            {
+                if ( test_bit(_PGC_need_scrub, &(pg-mask)->count_info) )
+                    break;
+            }
+            pg -= mask;
+            page_list_del(pg, &heap(node, zone, order));
+        }
+        else
+        {
+            /* Merge with successor block? */
+            if ( !mfn_valid(page_to_mfn(pg+mask)) ||
+                 !page_state_is(pg+mask, free) ||
+                 (PFN_ORDER(pg+mask) != order) ||
+                 (phys_to_nid(page_to_maddr(pg+mask)) != node) )
+                break;
+            if ( need_scrub )
+            {
+                if ( !test_bit(_PGC_need_scrub, &(pg+mask)->count_info) )
+                    break;
+            }
+            else
+            {
+                if ( test_bit(_PGC_need_scrub, &(pg+mask)->count_info) )
+                    break;
+            }
+            page_list_del(pg + mask, &heap(node, zone, order));
+        }
+
+        order++;
+    }
+
+    PFN_ORDER(pg) = order;
+    page_list_add_tail(pg, &heap(node, zone, order));
+}
+
 /* Free 2^@order set of pages. */
 static void free_heap_pages(
     struct page_info *pg, unsigned int order, bool_t need_scrub)
 {
-    unsigned long mask, mfn = page_to_mfn(pg);
+    unsigned long mfn = page_to_mfn(pg);
     unsigned int i, node = phys_to_nid(page_to_maddr(pg)), tainted = 0;
     unsigned int zone = page_to_zone(pg);
 
@@ -891,59 +953,7 @@ static void free_heap_pages(
         }
     }
 
-    /* Merge chunks as far as possible. */
-    while ( order < MAX_ORDER )
-    {
-        mask = 1UL << order;
-
-        if ( (page_to_mfn(pg) & mask) )
-        {
-            /* Merge with predecessor block? */
-            if ( !mfn_valid(page_to_mfn(pg-mask)) ||
-                 !page_state_is(pg-mask, free) ||
-                 (PFN_ORDER(pg-mask) != order) ||
-                 (phys_to_nid(page_to_maddr(pg-mask)) != node) )
-                break;
-            /* If we need scrub, only merge with PGC_need_scrub pages */
-            if ( need_scrub )
-            {
-                if ( !test_bit(_PGC_need_scrub, &(pg-mask)->count_info) )
-                    break;
-            }
-            else
-            {
-                if ( test_bit(_PGC_need_scrub, &(pg-mask)->count_info) )
-                    break;
-            }
-            pg -= mask;
-            page_list_del(pg, &heap(node, zone, order));
-        }
-        else
-        {
-            /* Merge with successor block? */
-            if ( !mfn_valid(page_to_mfn(pg+mask)) ||
-                 !page_state_is(pg+mask, free) ||
-                 (PFN_ORDER(pg+mask) != order) ||
-                 (phys_to_nid(page_to_maddr(pg+mask)) != node) )
-                break;
-            if ( need_scrub )
-            {
-                if ( !test_bit(_PGC_need_scrub, &(pg+mask)->count_info) )
-                    break;
-            }
-            else
-            {
-                if ( test_bit(_PGC_need_scrub, &(pg+mask)->count_info) )
-                    break;
-            }
-            page_list_del(pg + mask, &heap(node, zone, order));
-        }
-
-        order++;
-    }
-
-    PFN_ORDER(pg) = order;
-    page_list_add_tail(pg, &heap(node, zone, order));
+    merge_free_trunks(pg, order, node, zone, need_scrub);
 
     if ( tainted )
         reserve_offlined_page(pg);
-- 
1.7.10.4


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