[03/11] xen/page_alloc: Add static per-node counts of free pages

Commit Message

Alejandro Vallejo March 14, 2025, 5:24 p.m. UTC

These are effectively the sum of free memory in all zones of each node.
It's an optimization to avoid doing that operation frequently in
following patches that introduce exact-node claims.

Signed-off-by: Alejandro Vallejo <[e-mail]>
---
 xen/common/page_alloc.c | 7 +++++++
 1 file changed, 7 insertions(+)

Patch

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 49c3258169db..733b0300a767 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -485,6 +485,9 @@  static unsigned long node_need_scrub[MAX_NUMNODES];
 static unsigned long *avail[MAX_NUMNODES];
 static long total_avail_pages;
 
+/* Per-node counts of free pages */
+static unsigned long pernode_avail_pages[MAX_NUMNODES];
+
 static DEFINE_SPINLOCK(heap_lock);
 static long outstanding_claims; /* total outstanding claims by all domains */
 
@@ -1033,6 +1036,7 @@  static struct page_info *alloc_heap_pages(
 
     ASSERT(avail[node][zone] >= request);
     avail[node][zone] -= request;
+    pernode_avail_pages[node] -= request;
     total_avail_pages -= request;
     ASSERT(total_avail_pages >= 0);
 
@@ -1191,6 +1195,8 @@  static int reserve_offlined_page(struct page_info *head)
             continue;
 
         avail[node][zone]--;
+        ASSERT(pernode_avail_pages[node] > 0);
+        pernode_avail_pages[node]--;
         total_avail_pages--;
         ASSERT(total_avail_pages >= 0);
 
@@ -1515,6 +1521,7 @@  static void free_heap_pages(
     }
 
     avail[node][zone] += 1 << order;
+    pernode_avail_pages[node] += 1 << order;
     total_avail_pages += 1 << order;
     if ( need_scrub )
     {