@Mohit sorry, but there’s not enough information so we can help you. Please check How to Ask a Question
Also, as you mentioned GitHub, is it the Self Hosted version, or the Cloud one?
Please beware to only load test applications and websites that you own.
DoS’ing someone else’s endpoints is in direct violation of our T&C. Large players such as GitHub have countermeasures to block you, but smaller ones don’t and you’ll hurt them.