Information processing system

An information processing system comprising:

• a plurality of platforms;
• and
• a relay device comprising an expansion bus that connects between the platforms, wherein
• the platforms each comprise:
• a memory that stores transmit data to be transmitted to another platform through transactions occurring in the platform concerned;
• and
• a controller that:
• reads, from the memory, first transmit data to be transmitted to the another platform, and transmits the first transmit data to the another platform through a first transaction among the transactions via the expansion bus,
• determines whether a second transaction is occurring in the platform after completion of transmission of each of packets included in the first transmit data, the second transaction being higher in priority than the first transaction, and
• in response to occurrence of the second transaction, reads, from the memory, second transmit data to be transmitted to the another platform, transmits the second transmit data to the another platform through the second transaction via the expansion bus, and interrupts transmission of the first transmit data until completion of transmission of the second transmit data.