On Thu, 20 Nov 2014 21:26:32 +0530, Varun Sharma said:

Is any one know how tcp retransmission works inside kernel ?

Yes, somebody understands it. :) You usually get better answers with more specific questions - do you need help in understanding the basic theory (on which case, info outside the kernel is the best source)? Or did you look at it and there's a specific point you're confused about?