Make innodb_flush_log_at_trx_commit a settable global variable.

sql/ha_innodb.cc:
  Remove innobase_flush_log_at_trx_commit
  (set srv_flush_log_at_trx_commit directly).
sql/ha_innodb.h:
  Remove innobase_flush_log_at_trx_commit.
  Declare srv_flush_log_at_trx_commit.
sql/mysqld.cc:
  Bypass the innobase_flush_log_at_trx_commit variable.
storage/innobase/include/srv0srv.h:
  Change the type of srv_flush_log_at_trx_commit.
storage/innobase/srv/srv0srv.c:
  Change the type of srv_flush_log_at_trx_commit.

sql/ha_innodb.cc

@@ -168,7 +168,6 @@ char*	innobase_unix_file_flush_method		= NULL;
 /* Below we have boolean-valued start-up parameters, and their default
 values */
 
-uint	innobase_flush_log_at_trx_commit	= 1;
 ulong	innobase_fast_shutdown			= 1;
 my_bool innobase_log_archive			= FALSE;/* unused */
 my_bool innobase_use_doublewrite		= TRUE;
@@ -1517,7 +1516,6 @@ innobase_init(void)
 	srv_log_archive_on = (ulint) innobase_log_archive;
 #endif /* UNIV_LOG_ARCHIVE */
 	srv_log_buffer_size = (ulint) innobase_log_buffer_size;
-	srv_flush_log_at_trx_commit = (ulint) innobase_flush_log_at_trx_commit;
 
 	/* We set srv_pool_size here in units of 1 kB. InnoDB internally
 	changes the value so that it becomes the number of database pages. */
@@ -1974,7 +1972,7 @@ innobase_commit_complete(
 
 		trx->active_trans = 0;
 
-		if (srv_flush_log_at_trx_commit == 0) {
+		if (UNIV_UNLIKELY(srv_flush_log_at_trx_commit == 0)) {
 
 			return(0);
 		}

sql/ha_innodb.h

@@ -206,7 +206,6 @@ class ha_innobase: public handler
 };
 
 extern SHOW_VAR innodb_status_variables[];
-extern uint innobase_flush_log_at_trx_commit;
 extern ulong innobase_fast_shutdown;
 extern ulong innobase_large_page_size;
 extern long innobase_mirrored_log_groups, innobase_log_files_in_group;
@@ -243,6 +242,7 @@ extern ulong srv_n_free_tickets_to_enter;
 extern ulong srv_thread_sleep_delay;
 extern ulong srv_thread_concurrency;
 extern ulong srv_commit_concurrency;
+extern ulong srv_flush_log_at_trx_commit;
 }
 
 int innobase_init(void);

sql/mysqld.cc

@@ -402,6 +402,7 @@ extern ulong srv_n_free_tickets_to_enter;
 extern ulong srv_thread_sleep_delay;
 extern ulong srv_thread_concurrency;
 extern ulong srv_commit_concurrency;
+extern ulong srv_flush_log_at_trx_commit;
 }
 #endif
 #ifdef WITH_BERKELEY_STORAGE_ENGINE
@@ -5127,8 +5128,8 @@ Disable with --skip-innodb-doublewrite.", (gptr*) &innobase_use_doublewrite,
    (gptr*) &innobase_file_per_table, 0, GET_BOOL, NO_ARG, 0, 0, 0, 0, 0, 0},
   {"innodb_flush_log_at_trx_commit", OPT_INNODB_FLUSH_LOG_AT_TRX_COMMIT,
    "Set to 0 (write and flush once per second), 1 (write and flush at each commit) or 2 (write at commit, flush once per second).",
-   (gptr*) &innobase_flush_log_at_trx_commit,
-   (gptr*) &innobase_flush_log_at_trx_commit,
+   (gptr*) &srv_flush_log_at_trx_commit,
+   (gptr*) &srv_flush_log_at_trx_commit,
    0, GET_ULONG, OPT_ARG,  1, 0, 2, 0, 0, 0},
   {"innodb_flush_method", OPT_INNODB_FLUSH_METHOD,
    "With which method to flush data.", (gptr*) &innobase_unix_file_flush_method,

sql/set_var.cc

@@ -97,6 +97,7 @@ extern ulong srv_n_free_tickets_to_enter;
 extern ulong srv_thread_sleep_delay;
 extern ulong srv_thread_concurrency;
 extern ulong srv_commit_concurrency;
+extern ulong srv_flush_log_at_trx_commit;
 }
 
 /* WITH_NDBCLUSTER_STORAGE_ENGINE */
@@ -517,6 +518,9 @@ sys_var_long_ptr  sys_innodb_thread_concurrency("innodb_thread_concurrency",
                                                 &srv_thread_concurrency);
 sys_var_long_ptr  sys_innodb_commit_concurrency("innodb_commit_concurrency",
                                                 &srv_commit_concurrency);
+sys_var_long_ptr  sys_innodb_flush_log_at_trx_commit(
+                                        "innodb_flush_log_at_trx_commit",
+                                        &srv_flush_log_at_trx_commit);
 
 /* Condition pushdown to storage engine */
 sys_var_thd_bool
@@ -838,7 +842,6 @@ SHOW_VAR init_vars[]= {
   {sys_innodb_fast_shutdown.name,(char*) &sys_innodb_fast_shutdown, SHOW_SYS},
   {"innodb_file_io_threads", (char*) &innobase_file_io_threads, SHOW_LONG },
   {"innodb_file_per_table", (char*) &innobase_file_per_table, SHOW_MY_BOOL},
-  {"innodb_flush_log_at_trx_commit", (char*) &innobase_flush_log_at_trx_commit, SHOW_INT},
   {"innodb_flush_method",    (char*) &innobase_unix_file_flush_method, SHOW_CHAR_PTR},
   {"innodb_force_recovery", (char*) &innobase_force_recovery, SHOW_LONG },
   {"innodb_lock_wait_timeout", (char*) &innobase_lock_wait_timeout, SHOW_LONG },
@@ -858,6 +861,7 @@ SHOW_VAR init_vars[]= {
   {sys_innodb_table_locks.name, (char*) &sys_innodb_table_locks, SHOW_SYS},
   {sys_innodb_thread_concurrency.name, (char*) &sys_innodb_thread_concurrency, SHOW_SYS},
   {sys_innodb_thread_sleep_delay.name, (char*) &sys_innodb_thread_sleep_delay, SHOW_SYS},
+  {sys_innodb_flush_log_at_trx_commit.name, (char*) &sys_innodb_flush_log_at_trx_commit, SHOW_SYS},
   {sys_interactive_timeout.name,(char*) &sys_interactive_timeout,   SHOW_SYS},
   {sys_join_buffer_size.name,   (char*) &sys_join_buffer_size,	    SHOW_SYS},
   {sys_key_buffer_size.name,	(char*) &sys_key_buffer_size,	    SHOW_SYS},

storage/innobase/include/srv0srv.h

@@ -80,7 +80,7 @@ extern ulint	srv_n_log_groups;
 extern ulint	srv_n_log_files;
 extern ulint	srv_log_file_size;
 extern ulint	srv_log_buffer_size;
-extern ulint	srv_flush_log_at_trx_commit;
+extern ulong	srv_flush_log_at_trx_commit;
 
 extern byte	srv_latin1_ordering[256];/* The sort order table of the latin1
 					character set */

storage/innobase/srv/srv0srv.c

@@ -116,7 +116,7 @@ ulint	srv_n_log_groups	= ULINT_MAX;
 ulint	srv_n_log_files		= ULINT_MAX;
 ulint	srv_log_file_size	= ULINT_MAX;	/* size in database pages */
 ulint	srv_log_buffer_size	= ULINT_MAX;	/* size in database pages */
-ulint	srv_flush_log_at_trx_commit = 1;
+ulong	srv_flush_log_at_trx_commit = 1;
 
 byte	srv_latin1_ordering[256]	/* The sort order table of the latin1
 					character set. The following table is