- define and use VMCNT_{GET,SET,ADD,SUB,PTR} macros for manipulating

   vmcnts.  This can be used to abstract away pcpu details but also changes
   to use atomics for all counters now.  This means sched lock is no longer
   responsible for protecting counts in the switch routines.

Contributed by:		Attilio Rao <attilio@FreeBSD.org>

1 files changed, 24 insertions, 9 deletions

diff --git a/sys/sys/vmmeter.h b/sys/sys/vmmeter.h
index 793f32d..375a2ce 100644
--- a/sys/sys/vmmeter.h
+++ b/sys/sys/vmmeter.h
@@ -102,7 +102,18 @@ struct vmmeter {
 };
 #ifdef _KERNEL
 
-extern struct vmmeter cnt;
+extern volatile struct vmmeter cnt;
+
+#define	VMCNT	__DEVOLATILE(struct vmmeter *, &cnt)
+#define	VMCNT_SET(member, val)						\
+	atomic_store_rel_int(__CONCAT(&cnt.v_, member), val)
+#define	VMCNT_ADD(member, val)						\
+	atomic_add_int(__CONCAT(&cnt.v_, member), val)
+#define	VMCNT_DEC(member, val)						\
+	atomic_subtract_int(__CONCAT(&cnt.v_, member), val)
+#define	VMCNT_GET(member)	(__CONCAT(cnt.v_, member))
+#define	VMCNT_PTR(member)						\
+	__DEVOLATILE(u_int *, __CONCAT(&cnt.v_, member))
 
 /*
  * Return TRUE if we are under our reserved low-free-pages threshold
@@ -112,7 +123,8 @@ static __inline
 int
 vm_page_count_reserved(void)
 {
-    return (cnt.v_free_reserved > (cnt.v_free_count + cnt.v_cache_count));
+    return (VMCNT_GET(free_reserved) > (VMCNT_GET(free_count) +
+        VMCNT_GET(cache_count)));
 }
 
 /*
@@ -126,7 +138,8 @@ static __inline
 int
 vm_page_count_severe(void)
 {
-    return (cnt.v_free_severe > (cnt.v_free_count + cnt.v_cache_count));
+    return (VMCNT_GET(free_severe) > (VMCNT_GET(free_count) +
+        VMCNT_GET(cache_count)));
 }
 
 /*
@@ -143,7 +156,8 @@ static __inline
 int
 vm_page_count_min(void)
 {
-    return (cnt.v_free_min > (cnt.v_free_count + cnt.v_cache_count));
+    return (VMCNT_GET(free_min) > (VMCNT_GET(free_count) +
+        VMCNT_GET(cache_count)));
 }
 
 /*
@@ -155,7 +169,8 @@ static __inline
 int
 vm_page_count_target(void)
 {
-    return (cnt.v_free_target > (cnt.v_free_count + cnt.v_cache_count));
+    return (VMCNT_GET(free_target) > (VMCNT_GET(free_count) +
+        VMCNT_GET(cache_count)));
 }
 
 /*
@@ -168,8 +183,8 @@ int
 vm_paging_target(void)
 {
     return (
-	(cnt.v_free_target + cnt.v_cache_min) - 
-	(cnt.v_free_count + cnt.v_cache_count)
+	(VMCNT_GET(free_target) + VMCNT_GET(cache_min)) - 
+	(VMCNT_GET(free_count) + VMCNT_GET(cache_count))
     );
 }
 
@@ -182,8 +197,8 @@ int
 vm_paging_needed(void)
 {
     return (
-	(cnt.v_free_reserved + cnt.v_cache_min) >
-	(cnt.v_free_count + cnt.v_cache_count)
+	(VMCNT_GET(free_reserved) + VMCNT_GET(cache_min)) >
+	(VMCNT_GET(free_count) + VMCNT_GET(cache_count))
     );
 }