There is provided with an interface apparatus. The interface apparatus provides a shared cache for a plurality of processing units. A first port acquires data from a first processing unit included in the plurality of processing units. A second port outputs the data acquired from the first processing unit to a second processing unit included in the plurality of processing units. A cache caches the data acquired from the first processing unit. A controller controls, based on information acquired from the second processing unit, whether to write back data written in the cache to a memory different from the cache.