JP2000078556A - Server device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce number of data transfer times, to shorten a data transfer time and to improve the performance of a device by directly transferring data which is read from a disk to a buffer memory by way of the memory of a system space when a read system call to be executed in a user space is issued. SOLUTION: When the read system call is issued in a VOD server process which is executed in the user space, data is react from a hard disk 3 and obtained data is transferred from the system space to the memory of the user space. That is, when the read system call is issued, the disk device driver of the system space reads compression data from the hard disk 3 to a file system through a SCSI interface 2. Compression data which is read out in the file system is instantaneously transferred to the buffer memory 51 of a decoder board 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a server device for outputting video signals by reading out moving image data and audio data from a disk and transferring the data to a decoder.

[0002]

2. Description of the Related Art Conventionally, an MPEG-2 VOD (Video On D) which immediately provides a video signal requested by a user.
emand) In server development, MP for 1-4 channels
Data (stream) to multiple EG-2 decoder boards
In order to transfer the data, it is required that the data can be easily and immediately transferred from the server process to channel buffers (1 to 4 channels) in each decoder board. The MPEG-2 decoder board decodes the compressed data input to the buffer memory in the board and converts it into a video signal of the NTSC system or the like.

Here, a multitasking OS such as UNIX is used.
In order to construct a VOD server having a function of decoding a compressed image by using the disk drive, the disk device driver S1 in the system space S as shown in FIG. Data from the file space S2 in the system space S to the buffer memory 10 in the user space U.
Then, the compressed data is transferred, and then the compressed data is transferred from the user space U to the decoder device driver S3 in the system space S.

When this series of operations is realized by a server in a user space, a temporary buffer memory 10 is secured in a user area, and read out by a read system call to the hard disk 3 with a pointer to the buffer memory 10 as an argument. The compressed data is transferred to the buffer memory 10 in the user space U, and the data is transferred from the buffer memory 10 in the user space U to the decoder device by a write system call to the MPEG-2 decoder board 5 using the pointer of the buffer memory 10 as an argument. Delivered to driver S3. This driver S3
Thus, the data is written to the buffer memory of the decoder board 5 of the physical layer P.

[0005] FIG.
5 is a time chart showing the passage of time in the CPU for reading a fixed amount at a time and writing to the decoder board 5. When data is read from the hard disk 3, a rotation waiting time x due to the seek of the hard disk 3 is required, and a time y for reading data from the hard disk 3 + a time y for copying data from the system space S to the user space U is required. It takes time z to transfer data from the buffer memory to the buffer memory in the decoder board 5.

[0006]

In the conventional moving image and audio server apparatus, when reading the compressed data from the hard disk 3 and transferring it to the buffer memory in the decoder board 5, the file system of the system space S is read from the hard disk 3. S2, transferring the data from the system space S to the buffer memory 10 in the user space U, and then transferring the data from the user space U to the decoder device driver S3 in the system space S, thereby obtaining the data. Is the decoder board 5
Since the data is transferred to the buffer memory inside the device, the number of times of data transfer is large, and it takes time to transfer the data, thereby deteriorating the performance of the apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to reduce the number of data transfers when transferring data from a disk to a buffer memory in a decoder board, thereby reducing the number of data transfers. An object of the present invention is to provide a server device capable of improving the performance of the device by shortening the time.

[0008]

To achieve the above object, a first aspect of the present invention is a server apparatus for transferring data from the disk to a decoder and outputting a video signal, wherein a buffer memory of the decoder is provided. Means for arranging the space in the memory space of the server unit and mapping the space to the memory space of the user space, and when a read system call executed in the user space is issued, the system reads the data read from the disk. Direct transfer to the buffer memory via a space memory.

According to the first aspect, since the buffer memory is mapped in the memory space of the server process in the user space, when a read system call executed in the server process in the user space is issued,
Data is read from the disk to a memory in the system space, and then the data is directly transferred from the memory to a buffer memory of the decoder. Therefore, since the data is not exchanged with the server process in the user space, the number of times of data transfer can be reduced, and the data transfer time can be shortened.

According to a second aspect of the present invention, in the server device according to the first aspect, the data is MPEG-2 compressed data, and the decoder is an MPEG-2 decoder board.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the server device of the present invention. An SIS in which a CPU 1 for controlling various operations of a server and a hard disk 3 are connected to a bus 4 for transmitting data and control signals, etc.
A C interface 2 is connected to a decoder port 5 for decoding compressed data and converting it into a video signal.
The decoder port 5 has a buffer memory 51 for temporarily storing transfer data, and a decoder 52 for decoding data in the buffer memory 51 to produce a video signal.

FIG. 2 is a schematic diagram showing the flow of data which reads out compressed data from the hard disk 3 of the above-described apparatus and transfers the data to the buffer memory 51 of the decoder board 5.

The physical layer P includes a SCSI interface 2 to which a hard disk 3 storing data is connected, and a decoder board 5 to which data is transferred. In the system space S, a disk device driver S1, a file system S2, and a decoder device driver S
There are three. The VOD server process 100 exists in the user space U.

Next, the operation of this embodiment will be described. Also in this example, since a waiting time occurs when the compressed data is read from the hard disk 3 of the physical layer P and transferred to the decoder board 5, the data is stored in the buffer memory 51 of the decoder board 5 so that the reproduction is not interrupted during the waiting time. Forward. In order to service a plurality of channels, a buffer memory 51 having a larger capacity is prepared so that reproduction is not interrupted until the scheduled time.

The memory space of the buffer memory 51 in the decoder board 5 is mapped to the memory space of the VOD server process 100 in the user space U by using the map entry of the decoder device driver S3 existing in the system space S. Issue a read system call to the hard disk 3 using the pointer in the memory space as an argument.

At this time, when a read system call is issued by the VOD server process 100 executed in the user space U, data is first read from the hard disk 3 and the obtained data is transferred from the system space S to the user space U. At this time, since the memory space of the buffer memory 51 is mapped to the memory space of the server process 100 in the user space U, the data is transferred to the decoder board 5 mapped to the user space U. Data is directly transferred to the buffer memory 51.

That is, when the above read system call is issued, the disk device driver S1 in the system space S reads the compressed data from the hard disk 3 to the file system S2 via the SCSI interface 2. The compressed data read on the file system S2 is immediately transferred to the buffer memory 5 of the decoder board 5.
Transferred to 1.

FIG. 3 is a time chart for reading a fixed amount of data (stream) into the buffer memory 51 of the decoder board 5 at one time.

In FIG. 3, a is the rotation waiting time due to the disk seek, b is the prefetch time from the disk, c
Denotes a read time from the disk, and d denotes a transfer time from the system space S to the buffer memory 51 in the decoder board 5.

When a large-size read system call is issued, a plurality of small-size reads are performed as shown in the figure, and data is transferred to the buffer memory 51 of the decoder board 5 each time. When a continuous stream is read, it is often a continuous sector on the hard disk 3 due to the allocation algorithm of the file system S2. Therefore, explicit reading is performed to the hard disk 3 + SCSI interface 2 and the cache of the device driver S1. Data is transferred even when not in use. When the file system unit S2 has a cache, data can be read implicitly in accordance with the block allocation of the file.

Therefore, the prefetch period b shown in FIG.
And the period d during which data is being transferred to the buffer memory 51 of the decoder board 5 is overlapped, so that the disk reading time of the conventional system and the slight overhead time are reduced.
The data transfer up to can be completed.

According to the present embodiment, the decoder board 5
After mapping the memory space of the buffer memory 51 to the VOD server process 100 in the user space U, the VOD server process 10 running in the user space U
0, a read system call is issued, data exchange with the user space U is skipped, and the hard disk 3
Compressed data read out from the memory card can be directly transferred to the buffer memory 51 of the decoder board 5 via the system space S in a time period of about waiting time + disk reading time, and the data transfer time can be reduced. Therefore, the performance of the device can be improved.

As a result, the number of times data is transferred within a certain time increases, and more compressed data (stream) can be output. Further, since there is no need to allocate a buffer memory to the user space U, the capacity of the RAM (main storage) mounted on the CPU 1 can be reduced.

In the above embodiment, the data is read from the hard disk 3, but may be a DVD disk or the like, and the data to be transferred is not limited to the compressed data.

[0025]

As described above in detail, according to the server device of the present invention, the number of data transfers when data is transferred from a disk to a buffer memory in a decoder board is reduced to shorten the data transfer time. Thereby, the performance of the device can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a server device of the present invention.

FIG. 2 is a conceptual diagram showing a flow of data read from a hard disk by the device shown in FIG. 1 and transferred to a buffer memory of a decoder board.

FIG. 3 is a time chart showing a lapse of time when a fixed amount of data (stream) is read into a buffer memory of the decoder board shown in FIG. 1 at a time.

FIG. 4 is a conceptual diagram showing a flow of data to be read from a hard disk in a conventional server device and transferred to a buffer memory of a decoder board.

FIG. 5 is a timing chart showing a lapse of time during data transfer in a conventional server device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 SCSI interface 3 Hard disk 4 Bus 5 Decoder board 51 Buffer memory 52 Decoder 100 VOD server process P Physical layer S System space S1 Disk device driver S2 File system S3 Decoder device driver U User space

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Claims (2)

[Claims] 1. A server device for transferring data from a disk to a decoder and outputting a video signal, wherein a buffer memory of the decoder is arranged in a memory space of a server unit, and the space is mapped to a memory space of a user space. A server that, when a read system call executed in the user space is issued, transfers data read from the disk directly to the buffer memory via a memory in the system space. apparatus. 2. The server device according to claim 1, wherein said data is MPEG-2 compressed data, and said decoder is an MPEG-2 decoder board.