Information processing apparatus and memory control apparatus
AssigneeFujitsu Limited
InventorsKoichi MAEDA, Hiroyuki Wada
Life of this patent
Estimating the term…
Abstract
A memory control apparatus, in a case of receiving from a processor, under a condition where the number of cache memories retaining a copy of data stored in a main storage device is one, a notification to the effect that data retained in the cache memory is purged, updates directory information on a directory cache without accessing the main storage device when the data is not modified by the processor, and the directory information on the directory cache and directory information on the main storage device is determined to be different and the directory information on the main storage device is determined to be in a state indicating that the copy of the data is not retained by any processor in the state of coherence.
Claims7
An information processing apparatus, comprising:
- a main storage device that stores data and manages a state of the stored data as directory information;
- cache memories that retain a copy of the data stored in the main storage device;
- processors that perform a process by using the data retained in the cache memories;
- a directory cache that manages the directory information of the data stored in the main storage device separately from the main storage device, and manages coherence state information indicating a state of coherence between the directory information managed by the directory cache and the directory information managed by the main storage device;
- and
- a memory control apparatus that controls a data transfer between the cache memories and the main storage device based on the information managed by the directory cache,
- wherein when a single cache memory retains a copy of data stored in the main storage device and the memory control apparatus receives a notice that data retained in the cache memory is purged from any of the processor, the memory control apparatus updates the directory information on the directory cache and accesses the main storage device to perform a write-back of the directory information on the main storage device when the coherence state information indicates that the directory information on the directory cache and the directory information on the main storage device are different, and updates the directory information on the directory cache without accessing the main storage device when the data is not modified by the processor, the coherence state information indicates that the directory information on the directory cache and the directory information on the main storage device are different, and the directory information on the main storage device indicates that the copy of the data is not retained by any of the processors.
A memory control apparatus provided in an information processing apparatus including a main storage device that stores data and manages a state of the data as directory information, a plurality of cache memories that retain a copy of the data stored in the main storage device, a plurality of processors that perform a process by using the data retained in the cache memories, and a directory cache that manages the directory information of the data stored in the main storage device separately from the main storage device and manages information indicating a state of coherence between the self-managing directory information and the directory information managed by the main storage device, the memory control apparatus comprising:
- a transfer controller that controls a data transfer between the cache memories and the main storage device based on the information managed by the directory cache;
- an information updater that updates the directory information on the directory cache and accesses the main storage device to perform a write-back of the directory information on the main storage device when the directory information on the directory cache and the directory information on the main storage device is determined to be different in the state of coherence, and updates the directory information on the directory cache without accessing the main storage device when the data is not modified by the processor, and the directory information on the directory cache and the directory information on the main storage device is determined to be different and the directory information on the main storage device is determined to be in a state indicating that the copy of the data is not retained by any of the processors in the state of coherence when the memory control apparatus receives a notification to an effect that the data retained in the cache memory is purged from the processor under a condition where a number of cache memories retaining the copy of the data stored in the main storage device is one.
Dependencies are inferred from the claim text.