srv0srv.c, srv0srv.h:

  Change srv_flush_log_at_trx_commit to ulint, note that ibool is defined as ulint, so this is purely formal change
os0file.c:
  Start using unbuffered i/o again in Windows because sequential read using normal i/o was 4 times slower in XP

innobase/include/srv0srv.h

@@ -53,7 +53,7 @@ extern ulint	srv_n_log_files;
 extern ulint	srv_log_file_size;
 extern ibool	srv_log_archive_on;
 extern ulint	srv_log_buffer_size;
-extern ibool	srv_flush_log_at_trx_commit;
+extern ulint	srv_flush_log_at_trx_commit;
 
 extern byte	srv_latin1_ordering[256];/* The sort order table of the latin1
 					character set */

innobase/os/os0file.c

@@ -15,8 +15,6 @@ Created 10/21/1995 Heikki Tuuri
 
 #undef HAVE_FDATASYNC
 
-#undef UNIV_NON_BUFFERED_IO
-
 #ifdef POSIX_ASYNC_IO
 /* We assume in this case that the OS has standard Posix aio (at least SunOS
 2.6, HP-UX 11i and AIX 4.3 have) */
@@ -500,14 +498,25 @@ try_again:
 		}
 #endif			
 #ifdef UNIV_NON_BUFFERED_IO
-		attributes = attributes | FILE_FLAG_NO_BUFFERING;
+		if (type == OS_LOG_FILE && srv_flush_log_at_trx_commit == 2) {
+		        /* Do not use unbuffered i/o to log files because
+		        value 2 denotes that we do not flush the log at every
+		        commit, but only once per second */
+		} else {
+		        attributes = attributes | FILE_FLAG_NO_BUFFERING;
+		}
 #endif
 	} else if (purpose == OS_FILE_NORMAL) {
-		attributes = 0
+	        attributes = 0;
 #ifdef UNIV_NON_BUFFERED_IO
-			 | FILE_FLAG_NO_BUFFERING
+		if (type == OS_LOG_FILE && srv_flush_log_at_trx_commit == 2) {
+		        /* Do not use unbuffered i/o to log files because
+		        value 2 denotes that we do not flush the log at every
+		        commit, but only once per second */
+		} else {
+		        attributes = attributes | FILE_FLAG_NO_BUFFERING;
+		}
 #endif
-			;
 	} else {
 		attributes = 0;
 		ut_error;

innobase/srv/srv0srv.c

@@ -96,7 +96,7 @@ ulint	srv_n_log_files		= ULINT_MAX;
 ulint	srv_log_file_size	= ULINT_MAX;	/* size in database pages */ 
 ibool	srv_log_archive_on	= TRUE;
 ulint	srv_log_buffer_size	= ULINT_MAX;	/* size in database pages */ 
-ibool	srv_flush_log_at_trx_commit = TRUE;
+ulint	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