Albert Barnes Commentary 2 Chronicles 30:22

"And Hezekiah spake comfortably unto all the Levites that had good understanding [in the service] of Jehovah. So they did eat throughout the feast for the seven days, offering sacrifices of peace-offerings, and making confession to Jehovah, the God of their fathers." — 2 Chronicles 30:22 (ASV)

The “knowledge” intended is perhaps chiefly ritualistic and musical—such knowledge as enabled them to conduct the service of the sanctuary satisfactorily.

They did eat throughout the feast—literally, “they did eat the feast”; i.e., “they kept the feast,” which was essentially kept by the eating of unleavened bread. The Levites kept the feast during the full term appointed for it, never failing in their duties, but taking their part day after day, both in the sacrifice of the victims and in singing praises to God.