JP2010244303A - Memory management device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily secure a continuous large capacity memory space for handling large capacity image data etc. in an image forming apparatus. <P>SOLUTION: In a conventional virtual memory system, it is difficult to obtain a continuous large capacity memory due to fragmentation or the like caused by the capacity restriction of a memory to be obtained or a memory acquisition/release operation under OS management in order to mange a memory space by an OS. Then, this memory management device includes an OS-non-management-memory-region management part for assigning a physical memory space to a virtual memory space by dividing the physical memory space into an OS-management region and an OS-non-management region, and for making it possible to perform access from an application program to the OS-non-management region. Furthermore, an OS-memory-region management part can perform access from a kernel for a debugging application or the like through a window region to a non-management region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique of a memory utilization method in a virtual memory system.

  Normally, in a memory map configuration that is conscious of the virtual memory space, the physical memory handling is left to the mapping mechanism managed by the OS, so the amount of memory that can not be handled freely by the user and cannot be linked between processes. Is limited.

  In the memory space managed by the OS, the memory is finely consumed by the method of repeatedly using and releasing the memory, and fragmentation of the memory area occurs. For example, in a device that handles large-capacity image data such as an image forming apparatus. As a result, a continuous large-capacity memory could not be secured, which caused a slowdown in data processing.

  As a prior art, there is the following method for providing a virtual memory system that does not consume extra physical memory for a page table. The address translation table generator is connected to the system bus and is accessed by the CPU when a TLB (Translation Look-aside Buffer) miss occurs. Whenever access is received, a corresponding page table entry is generated according to a preset rule. By accessing the address translation table generator, it is not necessary to use an area in the memory. The page table generation rule in the address translation table generator can be set from the CPU (see Patent Document 1).

  However, the above method is a technique for suppressing the memory consumption of the page table, and the memory area secured by this method is a very small amount, and a continuous large-capacity memory required for image data handled by the image forming apparatus. Space cannot be secured.

JP 2004-355187 A

  The problem to be solved is that a large-capacity continuous data area used by the user in the virtual memory system could not be secured.

  The memory management device of the present invention is a memory management device that manages a memory area having a virtual memory space, and secures a part of the physical memory space as a management area managed by an operating system (OS). An OS management area access means for allocating a management area to a virtual memory space and enabling acquisition and release of the memory space by the operating system, and securing a non-management area outside the management area of the physical memory space as the non-management area Is allocated to a virtual memory space, and an OS non-management area access unit that enables acquisition and release of the memory space. The OS management area access unit enables the operating system to refer to the non-management area. A window area for performing data transfer to the OS non-management area of the memory via the window area. Characterized in that to enable the read and write.

  The image forming apparatus according to the present invention divides a physical memory space into a management area that can be managed by an operating system (OS) and a non-management area that is not managed, and allocates the management area to a virtual memory space and stores the management area in the management area. An OS memory area management unit that enables acquisition / release of a memory space, and an OS that allocates the non-management area to a virtual memory space and enables acquisition / release of the memory space in the non-management area from an application program A non-managed memory area management unit, and the OS memory area management unit has a window area for enabling the operating system to refer to the non-managed area, and passes through the window area to It is possible to read and write data to the OS non-management area of the memory.

  The OS memory area management unit of the image forming apparatus of the present invention may be characterized in that the size of the window area is minimized.

  The image forming apparatus of the present invention may further include a DMA transfer unit that can directly access the memory space of the unmanaged area from hardware.

  The image forming apparatus of the present invention may include a printing unit that transfers image data written in the non-management area by a DMA transfer unit and prints the image data.

The image forming apparatus of the present invention has a scanner unit that reads an image and converts it into image data, and the DMA transfer unit writes the image data converted by the scanner unit into the unmanaged area by DMA transfer. It may be a feature.

  The memory management device of the present invention is a memory management device that manages a memory area having a virtual memory space, and secures a part of the physical memory space as a management area managed by an operating system (OS). An OS management area access means for allocating a management area to a virtual memory space and enabling acquisition and release of the memory space by the operating system, and securing a non-management area outside the management area of the physical memory space as the non-management area Is allocated to a virtual memory space, and an OS non-management area access unit that enables acquisition and release of the memory space. The OS management area access unit enables the operating system to refer to the non-management area. A window area for performing data transfer to the OS non-management area of the memory via the window area. Characterized in that to enable the read and write.

  For this reason, a continuous large-capacity memory using the memory of the OS non-management area can be obtained without being affected by the memory acquisition capacity limitation due to the OS managing all the memory areas or the occurrence of memory fragmentation. Be available. Further, the OS management area access means can use the window area to access the non-management area from the kernel for debugging purposes.

  The image forming apparatus according to the present invention divides a physical memory space into a management area that can be managed by an operating system (OS) and a non-management area that is not managed, and allocates the management area to a virtual memory space and stores the management area in the management area. An OS memory area management unit that enables acquisition / release of a memory space, and an OS that allocates the non-management area to a virtual memory space and enables acquisition / release of the memory space in the non-management area from an application program A non-managed memory area management unit, and the OS memory area management unit has a window area for enabling the operating system to refer to the non-managed area, and passes through the window area to It is possible to read and write data to the OS non-management area of the memory.

  For this reason, a continuous large-capacity memory using the memory of the OS non-management area can be obtained without being affected by the memory acquisition capacity limitation due to the OS managing all the memory areas or the occurrence of memory fragmentation. Be available. Further, the OS management area access means can use the window area to access the non-management area from the kernel for debugging purposes.

  The OS memory area management unit of the image forming apparatus of the present invention may be characterized in that the size of the window area is minimized.

  For this reason, the address space secured in the window area overlaps with the real memory, and the memory area can be prevented from being compressed, and the real memory space can be used effectively.

  The image forming apparatus of the present invention may further include a DMA transfer unit that can directly access the memory space of the unmanaged area from hardware.

  For this reason, it is possible to read / write data to / from the memory in the unmanaged area at high speed by using high-speed memory access by DMA transfer.

  The image forming apparatus of the present invention may include a printing unit that transfers image data written in the non-management area by a DMA transfer unit and prints the image data.

  For this reason, a large-capacity data area is secured in the non-management area as image data for printing, and high-speed data transfer is possible, and high-speed data transfer corresponding to high performance of the printing unit is possible. .

  The image forming apparatus of the present invention has a scanner unit that reads an image and converts it into image data, and the DMA transfer unit writes the image data converted by the scanner unit into the unmanaged area by DMA transfer. It may be a feature.

  For this reason, large-capacity image data obtained by the scanner can be processed at high speed.

1 is a functional block diagram of an image forming apparatus (memory management apparatus) according to an embodiment of the present invention. (A) This is a memory map when all memory areas except for I / O according to the conventional example are under OS management. (B) It is a memory map in the memory management method which has a window area | region which is an area | region for the data reference by Example 1 of this invention. (C) A memory map in which the window area is minimized according to the second embodiment of the present invention. (A) It is an example of a memory use classification when the physical memory according to the embodiment of the present invention is 1 Gbyte. (B) It is an example of a memory use classification when the physical memory according to the embodiment of the present invention is 2 Gbytes. (C) It is an example of a memory use classification when the physical memory according to the embodiment of the present invention is 3 Gbytes. 5 is a flowchart of a memory management operation in an initialization operation when the power is turned on in the image forming apparatus (memory management apparatus) of the embodiment of the present invention. (B) It is a flowchart of the operation | movement at the time of the image reading by a scanner part.

  In a conventional virtual memory system, in order for the OS to manage the memory space, continuous large-capacity memory is acquired by limiting the amount of memory to be acquired or by fragmentation caused by memory acquisition / release operations under OS management. Although it is difficult to do so, an OS non-management memory that divides a physical memory space into an OS management area and an OS non-management area and allocates the physical memory space to a virtual memory space and enables access from the application program to the OS non-management area The problem was solved by having an area management section.

  The virtual memory system of the memory management device according to the first embodiment will be described using the memory map of the conventional example shown in FIG. 2A and the memory map of the first embodiment shown in FIG. Since the functional block configuration and operation flow of the first embodiment and the second embodiment are the same, the second embodiment will be described.

  In FIG. 2, PROG is an abbreviation for a program, APL is an application, and WIN is an abbreviation for a window area.

  In FIG. 2, the address space is in a range indicated by 32 bits, and the upper 8 bits of the address are represented by hexadecimal numbers such as “00” to “FF” in the figure. The remaining 24 bits are all “0” and are omitted.

  FIG. 2A is a memory map when all memory areas except for I / O according to the conventional example are under OS management. In this case, in the standard state, the user side can sufficiently handle the virtual space, but since all are under OS management, it is difficult to dynamically secure a continuous area such as a DMA transfer area. In addition, fragmentation occurs due to repeated acquisition and release of memory by management of the OS, and the user cannot take a large memory area.

  Therefore, a method is adopted in which a DMA transfer dedicated area is secured from the physical memory and is handled as a shared memory outside the OS management.

  The memory management apparatus of the first embodiment has a window area (WIND in the figure) which is an area for uniquely referring to a memory area outside OS management, as shown in FIG. 2B.

  The memory management device divides a physical memory space into a management area that can be managed by an operating system (OS) and a non-management area that is not managed, and allocates the management area to a virtual memory space to allocate the memory space in the management area. An OS memory area management unit that enables acquisition / release and an IOMEM (OS non-management area) that allocates the non-management area to a virtual memory space and enables acquisition / release of the memory space in the non-management area from an application program. A management memory area management unit), and divides the virtual address space into a management area and a non-management area (hereinafter also referred to as a shared memory).

  However, in this state, there is no access means from the OS side (kernel) to the address space of the unmanaged area (shared memory). Therefore, in the first embodiment, the address space of the management area (hereinafter referred to as “kernel space”) and the address space of the non-management area (hereinafter referred to as “user space”) can be handled from the kernel physical space. A window (WIND) area in which physical memory is mapped to an area shifted by a certain offset (1.2 GB from 0x94000000 to 0xE0000000 in FIG. 2B) is provided.

  By having this window area, debugging from the kernel space, cache flush operation to reflect writing from the user process, and data transfer by a non-DMA (Direct Memory Access) CPU can be easily executed. It becomes like this.

  A memory management system in the image forming apparatus according to the second embodiment of the present invention will be described below.

  In the memory management method in the image forming apparatus according to the first embodiment, the window area is as large as 1.2 GB (gigabytes), and thus the user usable area in the virtual space is greatly compressed.

  Therefore, the window area is reduced by limiting the reference to the data in the shared memory in the kernel space to the minimum necessary amount. As a specific example, a window area (192 MB from 0xD4000000 to 0xE0000000) is created as shown in FIG. As a result, it is possible to secure a sufficient user space while using memory for DMA transfer and other purposes.

  In the second embodiment, a memory area (user space) allocated to a user is secured by the following method.

  (1) A shared memory having a size for which the purpose of sharing in a process is clear in advance when an OS (Operating System) is initialized is secured in an area outside the OS management.

  (2) The memory outside the management area can be mapped to the user space without being restricted by the OS, and there is no possibility of a memory shortage when securing the memory from the user space. In addition, it is possible to map the memory more widely by out of OS management.

  (3) The above unmanaged area is reserved to effectively use the virtual memory, and the kernel virtual area for directly browsing the physical memory is reduced, but the physical memory secured in the unmanaged area is mainly DMA Since the possibility of direct reference is low by allocating to an area limited to hardware access, the disadvantage of this expansion is small.

  Furthermore, by having the minimum necessary window area, it is possible to access the user space (OS non-management area) from the kernel side as in the first embodiment. In the second embodiment, since the window area is smaller than that in the first embodiment, a sufficient amount of memory in the user space can be secured.

  The size of the minimum necessary area of the window area depends on the characteristics of the image forming apparatus device. The minimum amount required for direct DMA access by the device is determined by, for example, the size required for DMA transfer from the scanner in the image forming apparatus.

  Furthermore, when referring to the data transferred by DMA from the user application, a cache invalidation process is required to synchronize the CPU cache and the real memory. This cache invalidation requires a window area as a virtual address, and if it does not exist, dynamic reservation and release processing is required to maintain coherency, which affects processing performance. In order to avoid this, it is necessary to reserve an area for coherency use in advance in the window area.

  The necessary minimum amount of the window area is determined from the necessary area for the DMA transfer and the necessary area for the cache invalidation process for maintaining cache coherency.

  The fact that the shared memory space (OS non-management area) can be increased by minimizing the window area as in the second embodiment will be described with reference to the memory map of FIG.

  3A shows an example of memory usage allocation when the physical memory is 1 GB, FIG. 3B shows an example when the physical memory is 2 GB, and FIG. 3C shows an example when the physical memory is 3 GB. . When the physical memory amount is 1 GB or 2 GB, there is no duplication of addresses because the window area is in the memory address 0x80000000 or later. In this case, no problem occurs even if the window area is 1.2 GB as in the first embodiment or the window area is 192 MB as in the second embodiment.

  However, as shown in FIG. 3C, when the physical memory is 3 GB, the window area and the OS unmanaged memory area are used when the window area starts from 0x94000000 as in the first embodiment. Can't use all of the shared memory.

  However, since the window area is minimized as in the second embodiment and the start address is assigned to the memory after the final address 0xC0000000, such as 0xD4000000, address duplication does not occur, and FIG. ), For example, the OS management area can be as large as 320 MB and the OS non-management memory area can be as large as 2.7 GB. Therefore, when using large data such as image data in the image forming apparatus, It is very effective.

[Constitution]
An image forming apparatus (memory management apparatus) as Embodiment 2 of the present invention will be described below.

  FIG. 1 shows a functional block diagram of the image forming apparatus 101.

  The image forming apparatus 101 includes a scanner unit 111, an HDD (Hard Disk Drive) 113, a DMA (Direct Memory Access) transfer unit 115, a printing unit 117, a main memory 119, a control unit 120, software 121, an OS (Operating System) 123, An OS memory area management unit 125, an IOMEM (OS unmanaged memory area management unit) 127, an application program 129, a scanner data reading program 131, and a data compression program 133 are included.

  Each functional block will be described below.

  The scanner unit 111 scans image data and converts it into electronic data. Since the image data has a large size and it is necessary to secure the continuous memory area and write the image data, the DMA transfer unit writes the image data in the OS unmanaged memory area.

  An HDD (Hard Disk Drive) 113 is a secondary storage device using a rotating magnetic disk, and stores programs and data for operating the image forming apparatus.

  A DMA (Direct Memory Access) transfer unit 115 is a functional unit that allows data acquired by the scanner unit 111 to be directly written to and read from the main memory 119 without passing through a CPU (included in the control unit 120). is there. This enables high-speed data transfer.

  The printing unit 117 is a functional unit that prints image data on paper.

  The main memory 119 is composed of a DRAM (Dynamic Random Access Memory), and a storage device that stores the software 121 of the image forming apparatus 101 as a primary storage device as necessary, and stores data for writing / reading data. It is.

  The control unit 120 includes a CPU (Central Processing Unit) and a peripheral control circuit, and controls the operation of the image forming apparatus 101.

  The software 121 is software for controlling the operation of the image forming apparatus 101, and includes an OS (Operating System) 123, an application program 129, and the like. Details will be described later in each item.

  An OS (Operating System) 123 is basic software for managing and controlling the operation of hardware and software of the image forming apparatus 101. The OS 123 includes an OS memory area management unit 125 described in the next section.

  The OS memory area management unit (OS memory area management means) 125 allocates and allocates a memory area managed by the OS, and finds and acquires a free area when a memory use request is received from a program or the like. When done, free the area. In the conventional memory management method, the memory space except for a part of the I / O use area and the like is all managed by the OS memory area management unit 125. However, in this embodiment, the image forming apparatus uses a kernel or a program. The OS memory area management unit 125 manages only a part of the area.

  Further, the OS memory area management unit 125 generates a window area that is a shared address space for allowing the OS side (kernel) to access the user space when the apparatus is started up. The management area can be accessed.

  The IOMEM (OS unmanaged memory area management unit; OS unmanaged area access means) 127 is the most characteristic functional unit of the present invention, and excludes memory areas (not including I / O areas) that are unmanaged by the OS. ) And the memory area (OS unmanaged memory area) is allocated to the virtual memory space. For the allocation, the MMAP operation is performed to secure and allocate the memory. The memory area can be directly accessed by DMA from the hardware (scanner part or printing part), and the user program (application program 129) can acquire the memory area via IOMEM (malloc ()) Release (free ()) is possible.

  For example, the image data read by the scanner unit can be a very large value depending on the image size, resolution, color depth, and the like. The memory area is acquired / released directly from a program (for example, a scanner data reading program 131 described later).

  The application program 129 is a program necessary for operating the image forming apparatus 101, and includes, for example, a scanner data reading program 131, a data compression program 133, and other programs as shown in the next section. Details will be described in the next section.

  The scanner data reading program 131 realizes a function for causing the DMA transfer unit 115 to directly write large-capacity image data read by the scanner unit 111 to the main memory 119.

  The data compression program 133 realizes a function for compressing data such as image data.

[flowchart]
FIG. 4A shows a flowchart of the initialization operation of the image forming apparatus 101 according to the embodiment of the present invention. Each operation will be described below.

  S11: When the image forming apparatus is powered on, the OS 123 starts to operate, and the OS memory area management unit 125 secures a part of the area on the main memory 119 as the OS management area.

  S13: The IOMEM 127 maps the remaining memory area from the main memory for use by the continuous large-capacity memory and prepares for use from the user program.

  With the above series of operations, the memory initialization operation at the time of power-on is completed.

  FIG. 4B illustrates the use of the memory in the image forming apparatus 101 according to the embodiment of the present invention, taking as an example the operation when scanning image data.

  S21: The scanner unit 111 starts reading image data. At this time, the scanner data reading program acquires a large-capacity continuous memory area for writing image data via the IOMEM 127 in an OS unmanaged memory area on the main memory 119.

  S23: The image data read during the operation of S21 is transferred by the DMA transfer unit 115 to the OS unmanaged memory area acquired in S11.

  S25: The data compression program 133 accesses and reads the image data transferred to the OS unmanaged memory area via the IOMEM 127.

  S27: The data compression program 133 compresses the read image data and temporarily writes it in the OS management memory area.

  S 29: The data compression program 133 writes the compressed data temporarily written in S 27 to the HDD 113. In S27 and S29, the data written in the HDD by operating in parallel is erased from the memory, so that the OS memory area is not greatly consumed.

  Through the series of operations described above, a large-capacity OS unmanaged memory area secured by the IOMEM 127 can be used by the DMA transfer unit 115, the scanner data reading program 131, and the data compression program.

[Effect of Example]
The image forming apparatus according to the embodiment of the present invention enables the following.

  Since there is no need to have a window area for sharing memory between the user space and the OS-managed kernel space, the virtual memory space is consumed by the window area that is an overlapping address space in the virtual memory space. Is resolved.

  If all the memory areas are under the control of the OS, acquisition of the memory area (malloc ()) may be limited by the acquisition capacity size due to the restrictions of the OS. Disappear.

  Fragmentation occurs in the memory area under the management of the OS, and even if it is within the acquisition capacity size limit described above, a continuous memory area may not be acquired. By controlling the memory acquisition by the program), it is possible to prevent the occurrence of fragmentation and acquire a continuous large-capacity memory space.

  Since the OS non-management area can also be accessed from the OS side (for example, the kernel) via the window area, the kernel can also access the non-management area for debugging purposes.

[Others]
In the description of the embodiments of the present invention, the image forming apparatus has been described. However, the present invention is not limited to the image forming apparatus, and may be a memory management apparatus in an electronic apparatus having a memory.

101 Image forming apparatus (memory management apparatus)
111 Scanner unit 113 HDD (Hard Disk Drive)
115 DMA (Direct Memory Access) Transfer Unit 117 Printing Unit 119 Main Memory 120 Control Unit (including CPU)
121 Software 123 OS (Operating System)
125 OS memory area management unit (OS management area access means)
127 IOMEM (OS unmanaged memory area management unit; OS unmanaged area access means)
129 Application program 131 Scanner data reading program 133 Data compression program

Claims (6)

A memory management device for managing a memory area having a virtual memory space,
OS management area access means for securing a part of the physical memory space as a management area managed by the operating system (OS), allocating the management area to the virtual memory space, and enabling acquisition and release of the memory space by the operating system When,
OS non-management area access means for securing the outside of the management area of the physical memory space as a non-management area, allocating the non-management area to the virtual memory space, and enabling acquisition and release of the memory space,
The OS management area access means has a window area for allowing the operating system to refer to the non-management area, and reads data into the OS non-management area of the memory via the window area. And a memory management device capable of writing. The physical memory space is divided into a management area that can be managed by the operating system (OS) and a non-management area that is not managed, and the management area can be allocated to the virtual memory space to acquire and release the memory space in the management area An OS memory area management unit,
An OS unmanaged memory area management unit that allocates the unmanaged area to a virtual memory space and enables acquisition / release of the memory space in the unmanaged area from an application program;
The OS memory area management unit has a window area for enabling the operating system to refer to the unmanaged area, and reads data into the OS unmanaged area of the memory via the window area. And an image forming apparatus characterized by enabling writing. The image forming apparatus according to claim 2,
The image forming apparatus, wherein the OS memory area management unit minimizes the size of the window area. The image forming apparatus according to claim 2 or 3,
An image forming apparatus, comprising: a DMA transfer unit capable of directly accessing the memory space of the non-management area from hardware. The image forming apparatus according to claim 4,
An image forming apparatus, comprising: a printing unit configured to transfer image data written in the non-management area by the DMA transfer unit and print the image data. The image forming apparatus according to claim 4, wherein:
A scanner unit that reads an image and converts it into image data;
The DMA transfer unit writes the image data converted by the scanner unit into the non-management area by DMA transfer.

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