branches/zip bug#42885 rb://148

The call to put IO threads to sleep was most probably meant for Windows
only as the comment in buf0rea.c suggests. However it was enabled on
all platforms. This patch restricts the sleep call to windows. This
approach of not putting threads to sleep makes even more sense because
now we have multiple threads working in the background and it probably
is not a good idea to put all of them to sleep because a user thread
wants to post a batch for readahead.

Approved by: Marko

handler/ha_innodb.cc

@@ -171,9 +171,7 @@ file formats in the configuration file, but can only be set to any
 of the supported file formats during runtime. */
 static char*	innobase_file_format_check		= NULL;
 
-/* The following has a misleading name: starting from 4.0.5, this also
-affects Windows: */
-static char*	innobase_unix_file_flush_method		= NULL;
+static char*	innobase_file_flush_method		= NULL;
 
 /* Below we have boolean-valued start-up parameters, and their default
 values */
@@ -2155,7 +2153,7 @@ innobase_change_buffering_inited_ok:
 
 	/* --------------------------------------------------*/
 
-	srv_file_flush_method_str = innobase_unix_file_flush_method;
+	srv_file_flush_method_str = innobase_file_flush_method;
 
 	srv_n_log_groups = (ulint) innobase_mirrored_log_groups;
 	srv_n_log_files = (ulint) innobase_log_files_in_group;
@@ -9757,7 +9755,7 @@ static MYSQL_SYSVAR_ULONG(flush_log_at_trx_commit, srv_flush_log_at_trx_commit,
   " or 2 (write at commit, flush once per second).",
   NULL, NULL, 1, 0, 2, 0);
 
-static MYSQL_SYSVAR_STR(flush_method, innobase_unix_file_flush_method,
+static MYSQL_SYSVAR_STR(flush_method, innobase_file_flush_method,
   PLUGIN_VAR_RQCMDARG | PLUGIN_VAR_READONLY,
   "With which method to flush data.", NULL, NULL, NULL);
 

os/os0file.c

@@ -3371,9 +3371,21 @@ void
 os_aio_simulated_put_read_threads_to_sleep(void)
 /*============================================*/
 {
+
+/* The idea of putting background IO threads to sleep is only for
+Windows when using simulated AIO. Windows XP seems to schedule
+background threads too eagerly to allow for coalescing during
+readahead requests. */
+#ifdef __WIN__
 	os_aio_array_t*	array;
 	ulint		g;
 
+	if (os_aio_use_native_aio) {
+		/* We do not use simulated aio: do nothing */
+
+		return;
+	}
+
 	os_aio_recommend_sleep_for_read_threads	= TRUE;
 
 	for (g = 0; g < os_aio_n_segments; g++) {
@@ -3384,6 +3396,7 @@ os_aio_simulated_put_read_threads_to_sleep(void)
 			os_event_reset(os_aio_segment_wait_events[g]);
 		}
 	}
+#endif /* __WIN__ */
 }
 
 /*******************************************************************//**