File 19162-page-info-no-cpumask.patch of Package xen

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1233761391 0
# Node ID de853e901b5c6cfe3687404623c750b0f2c66058
# Parent  13a0272c8c024fca83bc991c7e2da992d07bc8eb
Remove cpumask for page_info struct.

This makes TLB flushing on page allocation more conservative, but the
flush clock should still save us most of the time (page freeing and
alloc'ing tends to happen in batches, and not necesasrily close
together). We could add some optimisations to the flush filter if this
does turn out to be a significant overhead for some (useful)
workloads.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1233835750 0
# Node ID 416197f0292b62425beb8277e122c41c645d9ab6
# Parent  3fc7d4115d6cd0ebf0cf55ed340da8a1b4c16592
Add a page_info flag to indicate whether free pages need a TLB flush
on next use.

Apart from teh small performance gain of this, my primary motivation
is to avoid TLB flushes very early in boot, when the system is not yet
properly set up for cross-TLB shootdowns.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -373,10 +373,13 @@ static struct page_info *alloc_heap_page
         /* Reference count must continuously be zero for free pages. */
         BUG_ON(pg[i].count_info != 0);
 
-        /* Add in any extra CPUs that need flushing because of this page. */
-        cpus_andnot(extra_cpus_mask, pg[i].u.free.cpumask, mask);
-        tlbflush_filter(extra_cpus_mask, pg[i].tlbflush_timestamp);
-        cpus_or(mask, mask, extra_cpus_mask);
+        if ( pg[i].u.free.need_tlbflush )
+        {
+            /* Add in extra CPUs that need flushing because of this page. */
+            cpus_andnot(extra_cpus_mask, cpu_online_map, mask);
+            tlbflush_filter(extra_cpus_mask, pg[i].tlbflush_timestamp);
+            cpus_or(mask, mask, extra_cpus_mask);
+        }
 
         /* Initialise fields which have other uses for free pages. */
         pg[i].u.inuse.type_info = 0;
@@ -398,7 +401,6 @@ static void free_heap_pages(
 {
     unsigned long mask;
     unsigned int i, node = phys_to_nid(page_to_maddr(pg));
-    struct domain *d;
 
     ASSERT(zone < NR_ZONES);
     ASSERT(order <= MAX_ORDER);
@@ -420,15 +422,10 @@ static void free_heap_pages(
          */
         pg[i].count_info = 0;
 
-        if ( (d = page_get_owner(&pg[i])) != NULL )
-        {
+        /* If a page has no owner it will need no safety TLB flush. */
+        pg[i].u.free.need_tlbflush = (page_get_owner(&pg[i]) != NULL);
+        if ( pg[i].u.free.need_tlbflush )
             pg[i].tlbflush_timestamp = tlbflush_current_time();
-            pg[i].u.free.cpumask     = d->domain_dirty_cpumask;
-        }
-        else
-        {
-            cpus_clear(pg[i].u.free.cpumask);
-        }
     }
 
     spin_lock(&heap_lock);
--- a/xen/include/asm-ia64/mm.h
+++ b/xen/include/asm-ia64/mm.h
@@ -63,21 +63,14 @@ struct page_info
         struct {
             /* Order-size of the free chunk this page is the head of. */
             u32 order;
-            /* Mask of possibly-tainted TLBs. */
-            cpumask_t cpumask;
+            /* Do TLBs need flushing for safety before next page use? */
+            bool_t need_tlbflush;
         } __attribute__ ((packed)) free;
 
     } u;
 
     /* Timestamp from 'TLB clock', used to reduce need for safety flushes. */
     u32 tlbflush_timestamp;
-
-#if 0
-// following added for Linux compiling
-    page_flags_t flags;
-    atomic_t _count;
-    struct list_head lru;	// is this the same as above "list"?
-#endif
 };
 
 #define set_page_count(p,v) 	atomic_set(&(p)->_count, v - 1)
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -72,8 +72,8 @@ struct page_info
 
         /* Page is on a free list: ((count_info & PGC_count_mask) == 0). */
         struct {
-            /* Mask of possibly-tainted TLBs. */
-            cpumask_t cpumask;
+            /* Do TLBs need flushing for safety before next page use? */
+            bool_t need_tlbflush;
         } free;
 
     } u;