WIP: Disable buf_page_t::access_time

mysql-test/suite/innodb_i_s/innodb_buffer_page_lru.result

@@ -11,7 +11,7 @@ INNODB_BUFFER_PAGE_LRU	CREATE TEMPORARY TABLE `INNODB_BUFFER_PAGE_LRU` (
   `IS_HASHED` int(1) NOT NULL DEFAULT 0,
   `NEWEST_MODIFICATION` bigint(21) unsigned NOT NULL DEFAULT 0,
   `OLDEST_MODIFICATION` bigint(21) unsigned NOT NULL DEFAULT 0,
-  `ACCESS_TIME` bigint(21) unsigned NOT NULL DEFAULT 0,
+  `ACCESS_TIME` bigint(21) unsigned DEFAULT NULL,
   `TABLE_NAME` varchar(1024) DEFAULT NULL,
   `INDEX_NAME` varchar(64) DEFAULT NULL,
   `NUMBER_RECORDS` bigint(21) unsigned NOT NULL DEFAULT 0,

storage/innobase/buf/buf0buf.cc

@@ -2512,7 +2512,6 @@ inline buf_page_t *buf_pool_t::watch_set(const page_id_t id,
   watch when setting another watch. */
   for (buf_page_t *w= &watch[UT_ARR_SIZE(watch)]; w-- >= watch; )
   {
-    ut_ad(w->access_time == 0);
     ut_ad(!w->oldest_modification());
     ut_ad(!w->zip.data);
     ut_ad(!w->in_zip_hash);
@@ -3002,7 +3001,6 @@ buf_page_get_low(
 	bool			allow_ibuf_merge)
 {
 	buf_block_t*	block;
-	unsigned	access_time;
 	ulint		retries = 0;
 	const ulint	fold = page_id.fold();
 
@@ -3356,9 +3354,7 @@ buf_page_get_low(
 		rw_lock_x_unlock(hash_lock);
 		buf_pool.n_pend_unzip++;
 
-		access_time = block->page.is_accessed();
-
-		if (!access_time && !recv_no_ibuf_operations
+		if (UNIV_UNLIKELY(!recv_no_ibuf_operations)
 		    && ibuf_page_exists(block->page.id(), zip_size)) {
 			block->page.ibuf_exist = true;
 		}

storage/innobase/handler/i_s.cc

@@ -116,7 +116,6 @@ struct buf_page_info_t{
 	ulint		block_id;	/*!< Buffer Pool block ID */
 	/** page identifier */
 	page_id_t	id;
-	unsigned	access_time:32;	/*!< Time of first access */
 	unsigned	io_fix:2;	/*!< type of pending I/O operation */
 	uint32_t	fix_count;	/*!< Count of how manyfold this block
 					is bufferfixed */
@@ -3996,8 +3995,7 @@ i_s_innodb_buffer_page_fill(
 		OK(fields[IDX_BUFFER_PAGE_OLDEST_MOD]->store(
 			   page_info->oldest_mod, true));
 
-		OK(fields[IDX_BUFFER_PAGE_ACCESS_TIME]->store(
-			   page_info->access_time, true));
+		fields[IDX_BUFFER_PAGE_ACCESS_TIME]->set_null();
 
 		fields[IDX_BUFFER_PAGE_TABLE_NAME]->set_null();
 
@@ -4168,8 +4166,6 @@ i_s_innodb_buffer_page_get_info(
 
 		page_info->oldest_mod = bpage->oldest_modification();
 
-		page_info->access_time = bpage->access_time;
-
 		page_info->zip_ssize = bpage->zip.ssize;
 
 		page_info->io_fix = bpage->io_fix() & 3;
@@ -4408,7 +4404,7 @@ static ST_FIELD_INFO	i_s_innodb_buf_page_lru_fields_info[] =
   Column("OLDEST_MODIFICATION",ULonglong(), NOT_NULL),
 
 #define IDX_BUF_LRU_PAGE_ACCESS_TIME	9 + I_S_AHI
-  Column("ACCESS_TIME",ULonglong(), NOT_NULL),
+  Column("ACCESS_TIME",ULonglong(), NULLABLE),
 
 #define IDX_BUF_LRU_PAGE_TABLE_NAME	10 + I_S_AHI
   Column("TABLE_NAME", Varchar(1024), NULLABLE),
@@ -4500,8 +4496,7 @@ i_s_innodb_buf_page_lru_fill(
 		OK(fields[IDX_BUF_LRU_PAGE_OLDEST_MOD]->store(
 			   page_info->oldest_mod, true));
 
-		OK(fields[IDX_BUF_LRU_PAGE_ACCESS_TIME]->store(
-			   page_info->access_time, true));
+		fields[IDX_BUF_LRU_PAGE_ACCESS_TIME]->set_null();
 
 		fields[IDX_BUF_LRU_PAGE_TABLE_NAME]->set_null();
 

storage/innobase/include/buf0buf.h

@@ -930,18 +930,8 @@ class buf_page_t
 					purposes without holding any
 					mutex or latch */
 	/* @} */
-	Atomic_counter<unsigned> access_time;	/*!< time of first access, or
-					0 if the block was never accessed
-					in the buffer pool.
-
-					For state==BUF_BLOCK_MEMORY
-					blocks, this field can be repurposed
-					for something else.
-
-					When this field counts log records
-					and bytes allocated for recv_sys.pages,
-					the field is protected by
-					recv_sys_t::mutex. */
+  /** used by recv_sys_t::add() only */
+  unsigned access_time;
   /** Change buffer entries for the page exist.
   Protected by io_fix()==BUF_IO_READ or by buf_block_t::lock. */
   bool ibuf_exist;
@@ -974,7 +964,6 @@ class buf_page_t
     buf_fix_count_= 0;
     old= 0;
     freed_page_clock= 0;
-    access_time= 0;
     oldest_modification_= 0;
     slot= nullptr;
     ibuf_exist= false;
@@ -1088,15 +1077,10 @@ class buf_page_t
   inline void set_old(bool old);
   /** Flag a page accessed in buf_pool
   @return whether this is not the first access */
-  bool set_accessed()
-  {
-    if (is_accessed()) return true;
-    access_time= static_cast<uint32_t>(ut_time_ms());
-    return false;
-  }
+  bool set_accessed() const { return false; }
   /** @return ut_time_ms() at the time of first access of a block in buf_pool
   @retval 0 if not accessed */
-  unsigned is_accessed() const { ut_ad(in_file()); return access_time; }
+  unsigned is_accessed() const { ut_ad(in_file()); return 0; }
 };
 
 /** The buffer control block structure */

storage/innobase/include/buf0buf.ic

@@ -100,23 +100,8 @@ inline bool buf_page_peek_if_too_old(const buf_page_t *bpage)
 		statistics or move blocks in the LRU list.  This is
 		either the warm-up phase or an in-memory workload. */
 		return(FALSE);
-	} else if (buf_LRU_old_threshold_ms && bpage->old) {
-		uint32_t access_time = bpage->is_accessed();
-
-		/* It is possible that the below comparison returns an
-		unexpected result. 2^32 milliseconds pass in about 50 days,
-		so if the difference between ut_time_ms() and access_time
-		is e.g. 50 days + 15 ms, then the below will behave as if
-		it is 15 ms. This is known and fixing it would require to
-		increase buf_page_t::access_time from 32 to 64 bits. */
-		if (access_time
-		    && ((ib_uint32_t) (ut_time_ms() - access_time))
-		    >= buf_LRU_old_threshold_ms) {
-			return(TRUE);
-		}
-
-		buf_pool.stat.n_pages_not_made_young++;
-		return false;
+	} else if (bpage->old && buf_LRU_old_threshold_ms) {
+		return true;
 	} else {
 		return !buf_page_peek_if_young(bpage);
 	}