JP2012155502A - Cache memory program resident in external recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a cache memory program resident in an external memory medium which effectively manages data in a computer utilizing apparatus such as a mobile phone, and enhances high-speed writing to the external memory medium and reading (transmitting) from the external memory medium up to capability of DRAM.SOLUTION: A cache memory program is automatically installed by mounting an external memory medium such as a micro SD memory card 1 on a computer utilization apparatus such as a mobile phone 2. A partial area of system memory 8 of the computer utilization apparatus is secured as virtual memory and cache memory 23 is assigned on the virtual memory and operated. By this way, writing/reading to/from CPU 7 etc. and writing/reading (transmitting) to/from the external memory medium are made possible, for any data in the computer utilization apparatus.

Description

  The present invention relates to a cache memory program resident (mounted) on an external recording medium.

  In the present specification and the like of the present application, a computer including a CPU, a system memory, an input / output unit, and the like, various computer terminals, a mobile phone, a navigation system, a digital camera, and the like are referred to as “computer utilizing devices”.

  Auxiliary storage devices such as a USB memory (USB is a registered trademark), an SD memory card (SD is a registered trademark), a micro SD memory card, a memory stick, and the like that can be attached to and removed from a computer-using device are referred to as an “external memory medium”. .

  In recent years, miniaturization of memory devices has progressed, and the background is the increase in capacity and cost of NAND flash memories. Since the NAND flash memory is a non-volatile memory, it is frequently used as an external memory medium such as a USB memory or an SD memory card as a data storage medium.

  Furthermore, a technology has been developed in which the external memory medium itself has not only a storage function but also a program and various control functions. For example, a configuration including a firmware storage unit capable of compressing / decompressing data in a memory card main body and a microprocessor for overall control thereof is known (see Patent Document 1).

JP 2005-293336 A

  By the way, the smaller the external memory medium is, the lower the number of NAND flash memories inside the external memory medium, the lower the input / output performance (I / O performance). In particular, the writing performance is extremely deteriorated to 0.005 MBps (4 KB at the time of random file) in the micro SD card.

  In addition, since the lifetime of the number of times of writing in the NAND flash memory is as small as several hundred times, it is necessary to consider the write restriction in operation.

  An object of the present invention is to solve the above-described conventional problems, and is a cache memory program that is resident in an external memory medium, and the apparatus is installed by mounting the external memory medium on a device such as a mobile phone. Installed on the device, efficiently managing the data in the device, enabling high-speed writing off to the external memory medium and transfer from the external memory medium, and preventing the loss or destruction of the data in the external memory medium, It is an object of the present invention to realize a cache memory program resident in an external memory medium that exhibits the function of extending the life.

  In order to solve the above problems, the present invention provides a cache memory program resident in an external memory medium that can be attached to and detached from a computer-using device, the computer-using device being attached to the computer-using device. At the same time, installation means for automatically installing and starting the cache memory program itself in the computer-using device, and uninstalling means for automatically uninstalling the cache memory program itself from the computer-using device at the same time that the external memory medium is removed from the computer-using device Cache memory area securing means for securing a part of the system memory as an area for a dedicated cache memory only when the external memory medium is mounted on a computer-using device, Write / read means for writing / reading data of the computer-using device as cache data, write-off means for writing down the cache data from the cache memory to the external memory medium, and reading out the cache data stored in the external memory medium from the external memory medium Provided is a cache memory program which functions as transfer means for transferring to a cache memory.

  The cache memory program according to the present invention confirms the attributes of a file including a file size for data input / output to / from a computer using a computer-based device, and based on the attribute information of the file, an external memory medium It may be configured to function as a writing condition creating means for determining the timing of writing to and the unit of the file.

  In the cache memory program according to the present invention, the area of the system memory allocated as an area for the cache memory by the cache memory area securing means is 64 MB or more, and the write-off means from the cache memory to the external memory medium is a series of cache data. Thus, the writing to the external memory medium is continuously executed in a short time to minimize the risk of the loss and destruction of the cache data caused by the power-off of the computer-using device or the unexpected removal of the external memory medium.

  In the cache memory program according to the present invention, the write-off means from the cache memory to the external memory medium functions to send the cache data to the controller in the external memory medium and cause the controller to temporarily store in a part of the external memory medium. It can also be made.

  The cache memory program according to the present invention has a plurality of modules corresponding to the OS of the computer utilizing device, and the installation means determines the OS of the computer utilizing device when an external memory medium is attached to the computer utilizing device. It is preferable to automatically execute a module corresponding to the OS.

  The cache memory program according to the present invention always describes the block addresses and data of all read / write events that occur in the computer-using device in the access history table, until the external recording medium is removed from the computer-using device. Preferably, the cache data block address information described in the access history table is stored in the memory in the external recording medium and functions as a block address information holding means for prefetching at the next installation.

  The external memory medium is a USB memory, an SD memory card, a micro SD memory card, or a memory stick, and the computer-using device can be applied to a computer terminal, a mobile phone, a digital camera, or a navigation system.

  The cache memory program according to the present invention allows a computer memory device to automatically operate a cache memory allocated on a virtual memory as a write buffer cache when a continuous write request has a file size larger than a certain value. The average write performance can be improved by fixing the cache policy to function as a means for caching even continuous data larger than the cache size. As a result, this cache effect does not occur in small continuous writing, and the starting point of this cache effect can be freely set.

The cache memory program according to the present invention mainly produces the following effects.
(1) By installing an external memory medium, it is automatically installed in the system memory in the computer-using device, a part of the system memory is secured as virtual memory, and cache memory is allocated on this virtual memory for operation. Therefore, the writing from the CPU, reading to the CPU, writing off to the external memory medium, and transfer from the external memory medium are raised to the performance of the DRAM.

(2) Since the block address information of a series of cache data written down from the system memory to the external memory medium is stored in the access history table resident in the external memory medium, when the external memory medium is attached to a computer-using device, The cache data at the time of the previous removal is automatically prefetched and resident in the cache memory.

(3) When writing cache data to an external memory medium, a series of cache data is continuously written to the external memory medium, so that the cache data can be written to the external memory medium in a short time and used by a computer. It is possible to minimize the risk of loss and destruction of cache data caused when the power of the device is cut off or the external memory medium is unexpectedly removed.

(4) The cache policy is fixed so that the cache memory allocated on the virtual memory automatically operates as a write buffer cache when the file size exceeds a certain value in a continuous write request. Even with continuous data, it has a function that produces a cache effect, which can improve the average write performance. As a result, this cache effect does not occur in small continuous writing, and the starting point of this cache effect can be freely set.

It is a figure explaining the Example of this invention, and shows the block diagram for demonstrating the whole structure of a micro SD memory card and a mobile telephone. FIG. 2 is a diagram for explaining an embodiment of the present invention, and shows a block diagram including a flow of cache data for schematically explaining the configuration of the cache memory program. It is a figure which shows the flow of the whole operation | movement of the cache memory program based on this invention. It is a figure which shows the flow of the cache memory program prefetching which concerns on this invention.

  An embodiment for implementing a cache memory program according to the present invention will be described below with reference to the drawings based on the embodiments.

(Overview)
The cache memory program according to the present invention is resident (installed) in an external memory medium that can be attached to and detached from the computer-using device, and is automatically installed in the system memory of the computer-using device when attached to the computer-using device. .

  The cache memory program according to the present invention automatically installed in this way is activated to secure a partial area of the system memory in the computer-using device as a virtual memory, and operates by allocating the cache memory on the virtual memory. Let

  Then, all data including download information from the Internet can be written to and read from the CPU, etc., further written off to the NAND flash memory (NAND FLASH MEMORY), and read (transfer) from the NAND flash memory. This is a cache memory program that can increase the performance of DRAM.

  In the present specification and the present invention, the overwriting of the external memory medium to the NAND flash memory will be described in the later-described embodiment, the explanation of the entire flow, etc., but the cache is not simply overwritten. Even after data is written down to a NAND flash memory (eg, a micro SD memory card), the same data as the data that has been written down is left in the cache memory. In short, it involves synchronizing the data.

  Therefore, the cache effect by rereading the data on the cache memory is maintained, and the effect is maintained until a new rewrite of data from the CPU or the like is requested, so that a memory area where new data can be overwritten becomes available.

  An embodiment of the present invention will be described with reference to FIGS. In this embodiment, a description will be given of an application example in which the external memory medium is a micro SD memory card, and the computer utilizing device in which the micro SD memory card is mounted is a mobile phone. Note that even when applied to other external memory media and computer-utilized devices, the configuration is the same and the same operation is performed.

(External memory media and computer equipment)
FIG. 1 is a diagram for schematically explaining the overall configuration of a micro SD memory card 1 and a mobile phone 2.

  FIG. 2 is a block diagram including the flow of cache data for schematically explaining the configuration of the cache memory program. The bold solid line indicates the main part of the hardware part of the mobile phone 2 related to the present invention and the main part of the micro SD memory card 1, and the thin line described part indicates that the cache memory program is the mobile phone 2 (specifically 1 schematically shows means that functions by operating the CPU) and important parts such as a flow of cache data by the means.

  The micro SD memory card 1 includes a plurality of NAND flash memories 3 and a controller 4. The controller 4 has a well-known configuration, assigns data to a plurality of NAND flash memories 3, reads data, and transfers (exchanges) data with a computer-using device. Among the plurality of NAND flash memories 3, A function of leveling the number of times of writing for each recording area by exerting control so that writing is not concentrated on a specific NAND flash memory 3 is exhibited.

  As shown in FIG. 2, a cache memory program according to the present invention is resident in a part of the NAND flash memory 3. In FIG. 2, the cache memory program is described as if it occupies one NAND flash memory 3, but actually it is resident in a part of one NAND flash memory 3.

  Further, as shown in FIG. 2, a part of the NAND flash memory 3 is allocated as a temporary storage area (TEMP memory area). When the power of the mobile phone 2 is shut off, the cache data in the mobile phone 2 is temporarily buffered in the temporary storage area by the controller 4, and the controller 4 later uses the micro SD memory card 1 (external memory medium). ) Are sequentially assigned and stored in the block addresses.

  The mobile phone 2 includes a CPU 7, a system memory (also referred to as “local memory”) 8, a north bridge (N / B) 9, a south bridge (S / B) 10, a bus (BUS) 11, an input / output unit (I / O) 12 and the like. Data is exchanged between the CPU 7 and the system memory 8 via the north bridge 9.

  The CPU 7 and the system memory 8 are connected to an external medium such as the micro SD card 1 through the south bridge 10 and the bus 11, and are further connected to the Internet 13 through a network. The system memory 8 stores an OS, application software, and the like.

(Cache memory program)
The configuration of the present invention will be described below with reference to FIG. 2, focusing on the cache memory program according to the present invention.

  The cache memory program according to the present invention resident in the micro SD memory card 1 automatically transfers the cache memory program itself to the system memory 8 of the mobile phone 2 when the micro SD memory card 1 is attached to the mobile phone 2. Then, the mobile phone 2 is caused to function as installation means 20 (see FIG. 2) that is automatically installed and activated in a part of the system memory 8 in the same manner as a normal user program.

  Specifically, the operation is performed by the CPU 7 of the mobile phone 2 (computer utilizing device) being installed and activated as described above according to the cache memory program.

  In the present specification and the invention, the cellular phone 2 (computer utilizing device) is caused to function as means for installing and starting up. Specifically, the CPU 7 of the cellular phone 2 (computer utilizing device) is connected to a cache memory. It is done by installing and starting the program according to the program. In the following, “to make the mobile phone 2 (computer using device) function as...” Specifically refers to the CPU 7 of the mobile phone 2 (computer using device) according to the cache memory program. It is performed by making the operation to do.

  Such a configuration in which the cache memory program resident in the micro SD memory card 1 is automatically mounted on the mobile phone 2 which is a computer utilizing device is one of the features of the cache memory program according to the present invention.

  Conventionally, a cache program used in a computer-based device is a kernel program (a core part of a hierarchically designed operating system (OS), which is a core part of the operating system (OS) of a computer-based device. A program that manages and manages the exchange of hardware and software components).

  Therefore, installation is absolutely necessary. Furthermore, since a part of the system memory is used as a cache memory, it is necessary to perform memory allocation (reserving a memory area) of the system memory in advance. In such a process, the OS must be restarted.

  However, although the cache memory program according to the present invention uses the system memory 8, the memory allocation of the OS is executed as one of user programs that do not need to be changed.

  In addition, the cache memory program causes the mobile phone 2 to function as uninstalling means 21 (see FIG. 2) for uninstalling the cache memory program itself at the same time that the micro SD memory card 1 is removed from the mobile phone 2.

  As described above, the cache memory program according to the present invention can be applied to various computer-based devices and various OSs installed in the devices by plug-and-play (implementation) using an implementation technology that does not require prior installation and uninstallation. It is possible to obtain a cache effect that does not depend on the OS of the computer-using device.

  The cache memory program according to the present invention automatically installs and starts the cache memory program itself in the system memory 8 of the mobile phone 2 when the micro SD memory card 1 is attached to the mobile phone 2. The mobile phone 2 is caused to function as the cache memory area securing means 22 that secures a virtual memory area in the unit.

  In other words, the installed cache memory program is activated and reads the OS and environmental conditions installed in the mobile phone 2, and in accordance with the read OS and environmental conditions, a virtual memory is partially stored on the system memory 8. A memory area used as a memory is secured.

  Then, the memory area secured on the system memory 8 is written to and read from the CPU 7 or the like for any data including download information from the Internet 13 in the mobile phone 2 under the cache memory program according to the present invention, The external memory medium can be assigned and used as a data-dedicated cache memory 23 that can be written to the NAND flash memory 3 and read (transferred) from the NAND flash memory 3.

  To explain this further, the cache memory program according to the present invention uses a virtual memory area secured in a part of the system memory 8 as the cache memory 23, and temporarily stores the data of the mobile phone 2 as cache data. Then, the cellular phone 2 is caused to function as the writing / reading means 24 for performing the reading operation as necessary.

  The area of the cache memory 23 is secured by 64 MB or more, and a block address is created on the cache memory 23 by a cache memory program, and data is based on the continuity and characteristics of input / output data (I / O file). Is assigned a block address, and is effectively written and held, and management of reading is executed.

  The writing / reading means 24 writes the data of the mobile phone 2 to the cache memory 23 by the write-back cache method as described above, and temporarily holds it as cache data. Then, if necessary, the cache data is read from the cache memory 23 and sent to the CPU 7, the input / output unit, and the like.

  Then, the cache memory program according to the present invention writes the cache data to the micro SD memory card 1 (transfers to the micro SD memory card 1 and stores it) at a predetermined write timing (see FIG. 2). Then, the mobile phone 2 is caused to function.

  Here, the determined write-off timing is determined according to the write-off condition. The cache memory program according to the present invention checks the attributes of the file including the file size, the cache data retention status in the cache memory 23, etc. for the data input / output to / from the cache memory 23, Below, the cellular phone 2 is caused to function as the writing condition creating means 26 (see FIG. 2) for determining the timing of writing to the cellular phone 2 (external memory medium) and the file unit.

  For example, a predetermined amount of an area reserved as the cache memory 23 (for example, when the entire area of the reserved cache memory 23 is 64 MB, for example, 20% of the area) holds cache data. When used, the cache data is transferred to the controller 4 of the micro SD memory card 1 using the free time of the CPU 7 and the writing is performed.

  This write-down operation will be described in the section “Overall operation flow” which will be described later, but will be further described here. When the write data of the cache memory 23 occupies a predetermined amount of the cache size (the amount of the entire area secured as the cache memory), the cache data is written down to the micro SD memory card 1 and is the same as the written-down data. Leave data in cache memory.

  In short, a process is performed in which cache data is written down to the micro SD memory card 1 and data stored in the cache memory is synchronized. In the cache memory, the remaining old data area is an area where new data can be rewritten from the CPU or the like in order from the previously written data area (an area where new data can be overwritten). It will be opened and reused.

  Further, after a certain period of time has elapsed after such synchronization processing, the unsynchronized cache data is synchronized with the micro SD memory card 1 by back-end task processing (see “Synchronize Data” above). As a result, all the cache memory is released as an area where data can be rewritten to the cache area (an area where new data from the CPU or the like can be overwritten).

  Then, the controller 4 of the micro SD memory card 1 temporarily buffers the cache data transferred at the time of writing in a temporary storage area (temporary storage area) allocated to a part of the NAND flash memory 3. Then, it is assigned to a block address in the memory and stored. Such an assignment operation is performed by a function assigned to the micro SD memory card 1.

  By the way, according to the cache memory program of the present invention, a series of cache data temporarily stored in the cache memory 23 is transferred to the controller 4 of the micro SD memory card 1 by a write-off algorithm such as a FIFO method. The data is continuously transferred (delivered), written in a temporary storage area, temporarily buffered, and later assigned to a block address in the memory for storage.

  In this way, a series of cache data is collectively written from the cache memory 23 to the micro SD memory card 1 and written down, thereby reducing the number of writes to the NAND flash memory 3. Therefore, it is possible to extend the life of the NAND flash memory 3 as compared with the conventional configuration in which cache data is sequentially written into the block address of the NAND flash memory of the micro SD memory card in small pieces.

  The conventional writing to the micro SD memory card by the Kernel program is a configuration in which the cache data is cut into pieces and written to the NAND flash memory of the micro SD memory card, so the power of the mobile phone 2 is shut off during the writing. If the micro SD memory card is removed unexpectedly, there is a risk that cache data may be lost or destroyed.

  However, according to the cache memory program of the present invention, a series of cached data is continuously delivered to the controller 4 of the micro SD memory card 1 and written to the micro SD memory card 1 (micro SD memory). Since the cache data is written to the card 1 in a single stroke, the time for writing the cache data to the external memory medium is reduced, and the power of the cellular phone (computer-using device) is cut off or the micro SD memory card is unexpectedly The risk of cache data loss and destruction due to removal of 1 (external memory medium) can be minimized.

  The cache memory program according to the present invention always describes the block address information of the cache data read from the cache memory 23 by the fifo method in the access history table, and the micro SD memory card 1 (external) from the mobile phone 2 (computer-using device). When the micro SD memory card 1 holds the cache data block address information described in the access history table when the memory medium is removed, and the micro SD memory card 1 is attached to the mobile phone 2, the cache data block The cellular phone 2 is caused to function as block address information holding means 27 (see FIG. 2) for prefetching and holding address information from the micro SD memory card 1 to the system memory 8.

  To further explain this configuration, the cache memory program according to the present invention stores the file number and the block address of the storage destination in the cache memory 23 area when the cache data is successively written in the cache memory 23 area. The mobile phone 2 is caused to function as block address information holding means 27 that records, updates, and stores as block address information in the resident access history table one after another in the order of writing.

  The block address information holding means 27 is resident in the area of the cache memory 23 each time the block address information at the time when the cache data is transferred from the cache memory 23 to the micro SD memory card 1 by the fifo method and written over. In the access history table, it is recorded and updated one after another in the order of writing, and stored as block address information.

  When the micro SD memory card 1 is removed from the mobile phone 2 by the block address information holding means 27, the micro SD memory card 1 is held in the micro SD memory card 1, and when the micro SD memory card 1 is attached to the mobile phone 2, the cache data block The address information is pre-read from the micro SD memory card 1 to the system memory 8 and stored in the access history table resident in the cache memory 23 area.

  The cache memory program according to the present invention is described in the access history table when the micro SD memory card 1 (external recording medium) is removed from the mobile phone 2 (computer utilization device) when the micro SD memory card 1 is attached to the mobile phone 2. As the transfer means 28 (see FIG. 2) for automatically transferring the cache data stored in the micro SD memory card 1 to the system memory 8 and reproducing it with the information on the block address of the cache data being stored downward, Make phone 2 work.

  This point will be further explained. The block address information read at the end before removing the micro SD memory card 1 (external recording medium) from the mobile phone 2 (computer-using device) is the NAND of the micro SD memory card 1 at the time of removal. The block address information held in the type flash memory 3 is pre-read and stored in an access history table resident in the system memory 8 of the mobile phone 2 when the micro SD memory card 1 is attached to the mobile phone 2.

  Therefore, when the micro SD memory card 1 is attached to the mobile phone 2, a series of cache data stored in the NAND flash memory 3 is automatically stored in the state when the micro SD memory card 1 was removed from the mobile phone 2 last time. Thus, it is possible to reproduce the state of the cache memory 23 to the state when the micro SD memory card 1 is removed from the mobile phone 2. This series of operations is performed in a process called prefetching. The operations by this prefetching will be further described with reference to FIG. 4 in the flow description to be described later.

  In this way, in a series of cache data write-off and read-out (transfer) processes from the system memory 8 to the micro SD memory card 1, the system memory 8 Since it is stored in the access history table resident in the memory, the cache performance (reading, writing speed, etc.) of the system memory 8 is improved to the DRAM performance without accessing the micro SD memory card 1. I can do it.

  In the cache memory program according to the present invention, in a continuous write request, the cache memory allocated on the virtual memory automatically operates as a write buffer cache when the file size exceeds a certain value. Is fixed, and the cache effect is generated regardless of the length of continuous data.

  This function can improve the average write performance. For example, even when the average write performance is 10 MBps, the effect of the above function is produced, so that an average continuous write performance of 15 MBps can be realized by the buffer function. On the other hand, it is characterized in that the start point of the cache effect can be freely set without being activated in small-scale continuous writing that does not reach a certain file size. As described above, there has never been a cache that has been implemented so as not to function at first but to function from a data file of a certain size.

(Overall operation flow)
The overall operation flow of the cache memory program according to the present invention will be described with reference to the flowchart shown in FIG.

(1) When the micro SD memory card 1 that is an external recording medium is inserted into the mobile phone 2 that is a computer-utilized device, the installer (installing means 20) is automatically activated (see FIG. 3A). . Thereby, the cache memory program is automatically installed in the system memory 8 of the mobile phone 2.

(2) The cache memory program is started, a partial area of the system memory 8 in the mobile phone 2 is secured as a virtual memory, the cache memory 23 is allocated on the virtual memory, and an operation (cache operation) is started (see FIG. 3 (b)).
(3) It is determined whether or not the write data of the cache memory 23 occupies a predetermined amount (for example, 90% as shown in FIG. 3) in the cache size (the amount of the entire area secured as the cache memory) (FIG. 3). (See (c)).

(4) As a result, if the cache size occupies a predetermined amount, the cache data is synchronized with the data to the micro SD memory card 1 and set in a rewritable area (see FIG. 3D). .

  Here, “synchronizing the cache data with the micro SD memory card 1” means that the cache data is written down to the micro SD memory card 1 and the same data as the written data is left in the cache memory. It is to leave. The remaining old data area is released as an area where new data can be rewritten from the CPU or the like (area where new data can be overwritten).

(5) Further, after a certain time has elapsed after the synchronization process, the unsynchronized cache data is synchronized with the micro SD memory card 1 by the back-end task process (see “Data synchronization” above). As a result, all the data is released as a memory as an area where data can be rewritten in the cache area. (See FIG. 3 (e)).

(6) If the cache size does not occupy a predetermined amount, the data is synchronized with the micro SD memory card 1 by performing back-end task processing when a predetermined time elapses as described above. Thus, all the memory is released as an area where data can be rewritten in the cache area (see FIG. 3 (e)).

(7) When the micro SD memory card 1 is removed from the mobile phone 2, it is determined whether or not the micro SD memory card 1 has been removed from the mobile phone 2 without performing proper processing (see FIG. 3). ).

(8) As a result, when the micro SD memory card 1 is removed from the mobile phone 2 without performing proper processing, the cache memory program automatically starts to be uninstalled. Does not remain (see FIG. 3 (K)).
(9) When normal processing is performed and the micro SD memory card 1 is removed from the mobile phone 2, the cache operation is continued (see FIG. 3).

(Prefetching flow)
By the way, as described above, the cache memory program according to the present invention is held in the micro SD memory card 1 when the external recording medium is removed from the computer-using device, and when the micro SD memory card 1 is attached to the mobile phone 2, the cache data As the block address information holding means 27 (see FIG. 2) for pre-reading and holding the block address information from the micro SD memory card 1 to the system memory 8, the mobile phone 2 is made to function and is stored in the access history table at the next installation. The block address information of the described cache data is pre-read on the cache memory 23 and made resident. This series of operations is performed by a process called prefetching. The prefetching flow will be described with reference to FIG.

(1) Information on the block address of cache data written to and read from the cache memory 23 is always registered in the access history table (see FIG. 4A).
(2) When the micro SD memory card 1 as an external recording medium is removed and the uninstallation of the cache memory program is started, the latest block address information at that time is stored in the access history table of the micro SD memory card 1 ( Refer to FIG.
(3) The uninstallation of the cache memory program is completed (see FIG. 4C).

(4) The next cache memory program is installed (see FIG. 4D).
(5) When the cache memory program is installed next time, it is determined whether or not the file size read-ahead in the cache memory 23 is larger than the cache size (see FIG. 4 (o)).

(6) As a result, when the prefetched file size is larger than the cache size (in the case of Y in FIG. 4), the micro SD memory card 1 to the cache memory 23 in order from the cache data of the last block address from the access history table. The prefetching is performed by prefetching (see FIG. 4F), and the prefetching is finished (see FIG. 4K).

(7) If the prefetched file size is not larger than the cache size (N in FIG. 4), the cache data of all block addresses from the access history table is prefetched from the micro SD memory card 1 onto the cache memory 23. And resident (see FIG. 4 (K)), and the prefetching is finished (see FIG. 4 (K)).

  As mentioned above, although the form for implementing the cache memory program which concerns on this invention was demonstrated based on the Example, this invention is not limited to such an Example, The technique described in the claim It goes without saying that there are various embodiments within the scope of the subject matter.

Specifically, the cache memory program according to the present invention as described above can be applied to various devices as follows, for example.
(1) General-purpose PC whose OS is Windows (registered trademark)
(2) Mobile phone 2 and mobile device resident ANDROID (registered trademark name) as OS (3) Mobile phone 2 and portable device resident IOS (registered trademark name) (4) Real-time OS resident device (5) Sensor Network (6) WiFi built-in SD card and its editing software (7) Home multimedia server (8) Device where Anti Virus software resides (9) Internet firewall device (10) Digital camera (11) Various networks Switch equipment

1 Micro SD memory card 2 Mobile phone 3 NAND flash memory 4 Controller 7 CPU
8 System memory 9 North bridge (N / B)
10 South Bridge (S / B)
11 Bus (BUS)
12 Input / output unit (I / O)
13 Internet
DESCRIPTION OF SYMBOLS 20 Installation means 21 Uninstallation means 22 Cache memory area securing means 23 Cache memory 24 Writing / reading means 25 Writing-out means 26 Writing-out condition preparation means 27 Block address information holding means 28 Transfer means

Claims (8)

A cache memory program resident in an external memory medium that can be attached to and detached from a computer-using device,
Computer-based equipment
Installation means for automatically installing and starting the cache memory program itself on the computer-using device at the same time that the external memory medium is mounted on the computer-using device;
Uninstalling means for automatically uninstalling the cache memory program itself from the computer-using device at the same time that the external memory medium is removed from the computer-using device,
Cache memory area securing means for securing a part of the system memory as a virtual memory and allocating the virtual memory as an area for a dedicated cache memory only when the external memory medium is mounted on a computer-using device,
In the cache memory, writing / reading means for writing and reading data of the computer-using device as cache data,
Write-down means to write down cache data from cache memory to external memory media,
Transfer means for reading cache data stored in an external memory medium from the external memory medium and transferring the cache data to the cache memory;
A cache memory program characterized by functioning as Computer-based equipment
Overwrite condition creation means for confirming file attributes including file size for data input / output to / from cache memory, and determining timing of writing to external memory medium and file unit based on attribute information of the file ,
The cache memory program according to claim 1, wherein the cache memory program functions as: The area of the system memory allocated by the cache memory area securing means as an area for the cache memory is 64 MB or more,
The means for overwriting from the cache memory to the external memory medium shortens the time to write the cache data to the external memory medium by continuously writing a series of cache data to the external memory medium, and shuts off the power supply of the computer equipment. 3. The cache memory program according to claim 1, wherein the risk of losing and destroying cache data due to unexpected removal of the external memory medium is reduced.   The write-down means from the cache memory to the external memory medium sends cache data to a controller in the external memory medium, and causes the controller to temporarily store in a part of the external memory medium. 2. The cache memory program according to 2 or 3.   The cache memory program has a plurality of modules corresponding to the OS of the computer-using device, and the installation means determines the OS of the computer-using device when an external memory medium is attached to the computer-using device, and 5. The cache memory program according to claim 1, wherein the corresponding module is automatically executed.   The block of the last cache data in which the computer device is always described in the access history table with all block address information read from and written to the cache memory, and the access history table when the external recording medium is removed from the computer device. Address information is held in a memory in an external recording medium, and functions as block address information holding means for prefetching and holding the block address information of the final cache data from the external recording medium to the cache memory at the next installation. 6. The cache memory program according to claim 1, wherein   The external memory medium is a USB memory, an SD memory card, a micro SD memory card, or a memory stick, and the computer-using device is a computer terminal, a mobile phone, a digital camera, or a navigation system. 7. The cache memory program according to any one of 6. Computer-based equipment
For continuous write requests, if the file size is larger than a certain value, the cache policy is fixed so that the cache memory allocated on the virtual memory automatically operates as a write buffer cache. However, the cache memory program according to any one of claims 1 to 7, wherein the cache memory program functions as a means for performing a cache.

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