Cache device, communication apparatus, and computer program product
First Claim
1. A cache device comprising:
- a first storage unit configured to store first cache data;
a second storage unit configured to store a cache file that stores copy of the first cache data as second cache data;
a reading unit configured to select and read out one of the first cache data, which has been stored in the first storage unit, and the second cache data, which has been stored in the cache file stored in the second storage unit, in response to a reference request from outside; and
an instructing unit configured to determine probability of expecting future referencing request based on the frequency of past referencing requests, the instructing unit being configured to instruct that either the first cache data or the second cache data is to be selected and read out based on the probability, the instructing unit being configured to calculate a probability P(t) of future referencing request expected at a time t in a future from a current point in time based on a following Equation (1);
P(t)=1−
exp(−
λ
×
t)
(1)wherein an average number of past referencing events per unit time is λ
.
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Accused Products
Abstract
A cache device may include a first storage unit configured to store first cache data, a second storage unit configured to store a cache file that stores copy of the first cache data as second cache data; a reading unit configured to select and read out one of the first cache data, which has been stored in the first storage unit, and the second cache data, which has been stored in the cache file stored in the second storage unit, in response to a reference request from outside, and an instructing unit configured to determine probability of expecting future referencing request based on the frequency of past referencing requests, the instructing unit being configured to instruct that either the first cache data or the second cache data is to be selected and read out based on the probability.
37 Citations
17 Claims
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1. A cache device comprising:
-
a first storage unit configured to store first cache data; a second storage unit configured to store a cache file that stores copy of the first cache data as second cache data; a reading unit configured to select and read out one of the first cache data, which has been stored in the first storage unit, and the second cache data, which has been stored in the cache file stored in the second storage unit, in response to a reference request from outside; and an instructing unit configured to determine probability of expecting future referencing request based on the frequency of past referencing requests, the instructing unit being configured to instruct that either the first cache data or the second cache data is to be selected and read out based on the probability, the instructing unit being configured to calculate a probability P(t) of future referencing request expected at a time t in a future from a current point in time based on a following Equation (1);
P(t)=1−
exp(−
λ
×
t)
(1)wherein an average number of past referencing events per unit time is λ
.- View Dependent Claims (2, 3, 4, 5)
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6. A communication apparatus that communicates with a field device;
- the communication apparatus comprising;
a device description file holding unit configured to hold parameter property information indicating characteristics of a parameter used in the field device; and a cache device comprising; a first storage unit configured to store device property information, which is obtained from the field device and indicates characteristics of the field device, and the parameter property information, which is obtained from the device description file holding unit, as first cache data; a second storage unit configured to store a cache file that stores copy of the first cache data as second cache data; a reading unit configured to select and read out one of the first cache data, which has been stored in the first storage unit, and the second cache data, which has been stored in the cache file stored in the second storage unit, in response to a reference request from outside; and an instructing unit configured to determine probability of expecting future referencing request based on the frequency of past referencing requests, the instructing unit being configured to instruct that either the first cache data or the second cache data is to be selected and read out based on the probability, the instructing unit being configured to calculate a probability P(t) of future referencing request expected at a time t in a future from a current point in time based on a following Equation (1);
P(t)=1−
exp(−
λ
×
t)
(1)wherein an average number of past referencing events per unit time is λ
.- View Dependent Claims (7, 8, 9, 10, 11, 12)
- the communication apparatus comprising;
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13. A computer program product embodied on a non-transitory computer readable medium, the computer program product comprising:
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instructions to store first cache data in first storage; instructions to store a cache file that stores copy of the first cache data as second cache data in second storage; instructions to select and read out one of the first cache data, which has been stored in the first storage, and the second cache data, which has been stored in the cache file stored in the second storage, in response to a reference request from outside; and instructions to determine probability of expecting future referencing request based on the frequency of past referencing requests and to instruct that either the first cache data or the second cache data is to be selected and read out based on the probability, instructions to calculate a probability P(t) of future referencing request expected at a time t in a future from a current point in time based on a following Equation (1);
P(t)=1−
exp(−
λ
×
t)
(1)wherein an average number of past referencing events per unit time is λ
.- View Dependent Claims (14, 15, 16, 17)
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Specification