An apparatus comprising: a plurality of requester elements to issue requests; at least one completer element to process the requests; a cache hierarchy comprising a plurality of levels of cache (15,25,35,50) to store cached copies of data associated with addresses in memory;; wherein: a given requester element in the plurality of requester elements is arranged to issue a cache maintenance operation request specifying a memory address range in order to cause a block of data associated with the specified memory address range to be pushed through at least one level of the cache hierarchy to a determined visibility point in order to make that block of data visible to one or more other requester elements in the plurality of requester elements; characterised in that the given requester element is responsive to detection of a need to issue a write request prior to the cache maintenance operation request in order to cause a write operation to be performed in respect of an item of data within the specified memory address range, to generate a combined write and cache maintenance operation request to be issued instead of the write request and subsequent cache maintenance operation request; wherein a recipient completer element amongst the at least one completer element that receives the combined write and cache maintenance operation request is arranged to initiate processing of a cache maintenance operation required by the combined write and cache maintenance operation request without waiting for the write operation to complete. a plurality of requester elements to issue requests; at least one completer element to process the requests; a cache hierarchy comprising a plurality of levels of cache (15,25,35,50) to store cached copies of data associated with addresses in memory;; wherein: a given requester element in the plurality of requester elements is arranged to issue a cache maintenance operation request specifying a memory address range in order to cause a block of data associated with the specified memory address range to be pushed through at least one level of the cache hierarchy to a determined visibility point in order to make that block of data visible to one or more other requester elements in the plurality of requester elements; characterised in that the given requester element is responsive to detection of a need to issue a write request prior to the cache maintenance operation request in order to cause a write operation to be performed in respect of an item of data within the specified memory address range, to generate a combined write and cache maintenance operation request to be issued instead of the write request and subsequent cache maintenance operation request; wherein a recipient completer element amongst the at least one completer element that receives the combined write and cache maintenance operation request is arranged to initiate processing of a cache maintenance operation required by the combined write and cache maintenance operation request without waiting for the write operation to complete. a given requester element in the plurality of requester elements is arranged to issue a cache maintenance operation request specifying a memory address range in order to cause a block of data associated with the specified memory address range to be pushed through at least one level of the cache hierarchy to a determined visibility point in order to make that block of data visible to one or more other requester elements in the plurality of requester elements; characterised in that the given requester element is responsive to detection of a need to issue a write request prior to the cache maintenance operation request in order to cause a write operation to be performed in respect of an item of data within the specified memory address range, to generate a combined write and cache maintenance operation request to be issued instead of the write request and subsequent cache maintenance operation request; wherein a recipient completer element amongst the at least one completer element that receives the combined write and cache maintenance operation request is arranged to initiate processing of a cache maintenance operation required by the combined write and cache maintenance operation request without waiting for the write operation to complete.