calculate the real number of pages used by segments and use it for killbig and proc

sys/src/9/port/segment.c

@@ -510,6 +510,27 @@ ibrk(ulong addr, int seg)
 	return 0;
 }
 
+/*
+ *  called with s->lk locked
+ */
+int
+mcountseg(Segment *s)
+{
+	int i, j, pages;
+	Page **map;
+
+	pages = 0;
+	for(i = 0; i < s->mapsize; i++){
+		if(s->map[i] == 0)
+			continue;
+		map = s->map[i]->pages;
+		for(j = 0; j < PTEPERTAB; j++)
+			if(map[j])
+				pages++;
+	}
+	return pages;
+}
+
 /*
  *  called with s->lk locked
  */