Which festival is mentioned in the poem "Cold Food Home"?

Cold food festival, that is, cold food festival, also known as "smoke-free festival", "cold food festival" and "Hundred Five Festival". April 4th every year, the day before Tomb-Sweeping Day. On this day, we don't smoke, but only eat cold food, which is called "Cold Food Festival". In the development of later generations, the customs of sweeping, hiking, swinging, cuju, pulling hooks and breaking eggs were gradually increased. The Cold Food Festival lasted for more than 2,000 years and was once called the largest folk festival. Many scholars have written poems about the Cold Food Festival.