关于mysql redo log的问题。

Question

http://bugs.mysql.com/bug.php?id=73202
上面是一个官方的patch,
According to the crash recovery logic of mysql server, we only need to write/sync prepared transaction before writing to binlog. And currently transactions are not grouped during innodb prepare stage.

I changed the related code described as bellow:

1. don’t sync redo log during innodb prepare stage if binlog enabled.

2. during flush stage of group commit (In function process_flush_stage_queue)
   a) collect group commit queue

b) call ha_flush_logs to sync redo log (make sure all redo log of prepared transaction in current
queue were synced before writing to binlog)
--innobase_flush_logs have to be changed.

c) flush thread cache to binlog file for every thd in queue

这段话我并不是很明白其中的意思，跪求mysql达人指点，我要的不是直接的翻译，而是要解释一下这段话在说明一个什么问题。