As a rule of thumb, the innodb_log_file_size is supposed to be 25% of innodb_buffer_pool_size. In your case, you should add that variable as follows:
Click Here to Learn to Resize innodb_log_file_size -> https://dba.stackexchange.com/a/1265/877
Here is a way you can setup the correct size of innodb_buffer_pool_size based on the amount of InnoDB Data you currently have. Run this query:
FROM (SELECT SUM(data_length+index_length) KBS FROM information_schema.tables
WHERE engine='InnoDB') A,
(SELECT 2 PowerOf1024) B;
recommended_innodb_buffer_pool_size comes back more than 75% of installed RAM, then use 75% of installed RAM as the recommended value. As mentioned before, set the innodb_log_file_size accordingly.