ha_innobase.cc, ha_innobase.h:

  innodb_flush_log_at_trx_commit can have values 0, 1, 2 starting from 3.23.52

sql/ha_innobase.cc

@@ -103,11 +103,18 @@ char*	innobase_unix_file_flush_method		= NULL;
 /* Below we have boolean-valued start-up parameters, and their default
 values */
 
-my_bool innobase_flush_log_at_trx_commit	= FALSE;
 my_bool innobase_log_archive			= FALSE;
 my_bool	innobase_use_native_aio			= FALSE;
 my_bool	innobase_fast_shutdown			= TRUE;
 
+/* innodb_flush_log_at_trx_commit can now have 3 values:
+0 : write to the log file once per second and flush it to disk;
+1 : write to the log file at each commit and flush it to disk;
+2 : write to the log file at each commit, but flush to disk only once per
+second */
+
+int     innobase_flush_log_at_trx_commit	= 0;
+
 /* The following counter is used to convey information to InnoDB
 about server activity: in selects it is not sensible to call
 srv_active_wake_master_thread after each fetch or search, we only do

sql/ha_innobase.h

@@ -176,8 +176,9 @@ extern long innobase_force_recovery, innobase_thread_concurrency;
 extern char *innobase_data_home_dir, *innobase_data_file_path;
 extern char *innobase_log_group_home_dir, *innobase_log_arch_dir;
 extern char *innobase_unix_file_flush_method;
+extern int innobase_flush_log_at_trx_commit;
 /* The following variables have to be my_bool for SHOW VARIABLES to work */
-extern my_bool innobase_flush_log_at_trx_commit, innobase_log_archive,
+extern my_bool innobase_log_archive,
                innobase_use_native_aio, innobase_fast_shutdown;
 
 extern TYPELIB innobase_lock_typelib;