How to increase the mappers and reducers in hadoop according to number of instances used to increase the performance?

Question

If I increase the number of mappers and decrease the number of reducers, then is there any difference in the performance (increase/decrease) of any job while execution?

Answer 1

I have tried the suggestion from @Animesh Raj Jha by modifying mapred.max.split.size and got a noticeable performance increase.