Maintaining snoop traffic throughput in presence of an atomic operation a first port for a first queue tracks cache requests and a second port for a second queue snoops that have yet to be filtered

An apparatus for filtering snoops without stalling during an atomic operation, the apparatus comprising:

• a first request queue storing an entry for each cache access request, each entry of the first request queue including a first set of address bits and an atomic bit, the first set of address bits indicating a first cache address associated with the cache access request, the atomic bit indication whether the cache access request is associated with the atomic operation;
• a second request queue storing an entry for each snoop to be filtered, each entry of the second request queue including a second set of address bits, the second set of address bits indicating a second cache address associated with the snoop;
• a cache with a first port and a second port, the first port being a data-and-tag port dedicated to the first request queue and the second port being a tag-only port dedicated to the second request queue, the cache permitting simultaneous access by the first and the second port to a same address during a same clock cycle.