JPS6393055A - Real time type garbage collection back-up device - Google Patents

Abstract

PURPOSE:To realize the real time type garbage collection at a high speed and with high object efficiency by simplifying decision of conditions done when a symbol processing program is executed in the form of the load and store instructions to be given to an external register. CONSTITUTION:The head address of a memory area equivalent to the present new space is written to an external register 203. When an entrance argument is needed at the entrance of an incorporated function or predicate, the relevant argument is written to a register 203. Then comparators 204 and 205 work with said argument writing timing. The comparator 205 outputs '1' when the pointer written to an external register 202 is larger than the end address written to the register 203. Therefore the output of an AND circuit 206 is equal to '1' as long as said pointer is kept between the head address and the end address. Then an argument pointer indicates a new space and no interruption is produced to a CPU 310. When the argument pointer indicates an old space, a control circuit 221 applies an interruption to the CPU 310 via an interruption request signal line 333.

Description

[Detailed description of the invention] [100th] Overview Industrial field of application Conventional technology Problems to be solved by the invention Means for solving the problems Example of action ■ Correspondence between the example and Fig. 1 Relationship ■, Structure of the embodiment ■, Operation of the embodiment ■1 Variations of the invention Effects of the invention [Summary] The present invention is a real-time garbage collection method that alternately performs execution of a symbolic processing program and garbage collection. This is a support device that uses hardware to detect the storage space position in the data storage area and the state of data movement from the old character to the new space, and performs interrupt processing to the central processing unit. This allows type garbage collection to be performed at high speed and the size of the program code to be compact.

[Industrial application field]

The present invention relates to a real-time garbage collection support device for rLIsPJ, rPrologJ, and other symbolic processing languages.

In rLIsPJ, rPrologJ, and other symbolic processing languages, storage space is wasted because storage space is dynamically allocated during program execution. Therefore, garbage collection is a process that collects storage areas that are no longer needed and returns them to unused areas for reuse.
ction) is required.

[Conventional technology]

Conventionally, a batch garbage collection method has been used in which when a storage area is used up, a program that performs symbolic processing is temporarily suspended, and the storage area is collected and reused all at once.

However, in recent years, as rLIsPJ, rPro 1ogJ, and other symbolic processing languages have been used for practical applications (for example, plant control), long interruptions of symbolic processing programs during garbage collection operations have become a problem. To solve this problem, there has been a need for a real-time garbage collection method that alternately performs symbol processing and storage area recovery to shorten the interruption of symbol processing programs due to garbage collection as much as possible.

Real-time garbage collection methods include paker (
Baker's algorithm has been announced, which is an evolution of the bulk garbage collection method using the copy method.

FIG. 4 is a diagram illustrating a batch garbage collection method using the copy method. FIG. 4(a) is a conceptual diagram thereof, and FIG. 4(bl) is an explanatory diagram of its operation.

In the copy method, the storage area is divided into two spaces, and the symbol processing program uses one of the spaces to proceed.

When the storage area currently being used by the symbol processing program is used up, the symbol processing program is interrupted and garbage collection is activated. Garbage collection recovers wasteful writing ↑α area by moving only valid data 411 that can be referenced from the symbol processing program from the old character space 410 that has used up the storage area to the new space 420. When all valid data has been moved, the interrupted symbol processing program is restarted, and data references are made to the valid data 421 in the new space 420 (425).

On the other hand, the real-time garbage collection method using Paker's algorithm limits the movement of valid data to a finite number k at a time after one storage area is used up, and The feature is that the interruption of the symbol processing program due to garbage collection can be kept short by dividing it into multiple times in parallel.

FIG. 5 is a diagram illustrating a real-time garbage collection method using Paker's algorithm. Figure 5 (a
1 is its conceptual diagram, and FIG. 5 (bl is its operation explanatory diagram).

Unlike the batch type, which completely suspends the symbolic processing program and moves the data all at once to switch spaces, the real-time garbage collection method moves the data in parts, dividing the data into pieces, so garbage collection starts immediately. Garbage collection and symbol processing programs will be executed alternately between the time the program is executed and the program terminates.

That is, data reference from the symbol processing program is first made to the old character space 510, and it is checked whether the referenced valid data 511, 512 has been moved to the new space 520 or has not yet been moved. If it has been moved, the valid data 521 in the new space 520 specified by the pointer is referenced.

Therefore, according to Paker's algorithm, interruption of the symbol processing program due to garbage collection can be suppressed within a finite time.

References 2. Henry G. Paker, Jr., "Real-Time List Processing Method," Communications of the ACM, No. 21t' 1978, (Ilenr.
y G, Baker+Jr, +”Li5t Proc
essing in RealTime on a 5
erial Computer” Communica
tion of the ACM, Vol 2L 19
78) [Problem to be solved by the invention] However, in real-time garbage collection using Paker's algorithm, while the symbol processing program and garbage collection are being executed alternately,
Data referenced from the symbol processing program is in the concave space 51
0 and new space 520. Furthermore, if the referenced data is in the concave space, there is a possibility that the data has already been moved to the new space by garbage collection operations.

Therefore, in order for a symbolic processing program to operate correctly, all data visible to the program must be
We need to ensure that it is within 20.

In other words, ``At the entrance to all built-in functions and predicates of LISPJ, rPro logJ, and other processing systems, ■ perform a pointer check on the argument, find out whether the pointer points to data in the old or new space, and ■ check the concave space. If the data has already been moved by garbage collection, update the argument pointer to point to that location; ■ If the data has not yet been moved, move the data to a new space and update the argument pointer. It means to become.

Here, the operation (■) is also necessary in the case of batch garbage collection, and there is no particular problem because it is returned as part of the garbage collection work. However,■
Judging the condition is a completely useless operation, especially when garbage collection is not in progress, and operation (2) is also unnecessary in batch garbage collection.

In this way, real-time garbage collection using the Paker algorithm requires operations (1) and (2) in particular, which causes the speed of the processing system to drop significantly compared to batch garbage collection.

Here, for example, r which is a basic function of rLIsPJ language
In the case where CARJ is implemented by the assembler of the microprocessor MC68000, a comparison will be made between wasteful garbage collection and real-time garbage collection. rcARj is a function that instructs to return the first element of a list structure when a manually entered pointer points to it, and is frequently used in symbol processing programs.

FIG. 6 is a diagram illustrating an example of implementation in the case of a processing system having -discard type garbage collection.

Here, it is assumed that the argument 601 is input to the function using the stack 602 and placed at a position above the pointer register (fp) by a displacement d, and the function value is returned in the register.

That is, the code is: CAR: move, l #d(fd), aOmove, 1
(ao), aO. In this case, the number of clocks required for execution is 28
, and the amount of code when the program is compiled (
The object size) is 6 bytes.

FIG. 7 is a diagram showing an implementation example based on Payker's algorithm.

In this case, the number of instructions increases for processing (1) and (2) above, and for passing arguments to the subroutine that performs the movement. That is, the argument 701 is input to the function using the stack 702, with the address placed at a higher position by a displacement d from the pointer register <f d). It is determined whether the argument pointer points to the new space or the old space. Furthermore, the data tag 703 of the displacement d'' is read to determine whether or not it has been moved to the new space.

The above code is: CAR: move, 1 1td (fd), ao; read arguments cmp, 1 11EAP TOP, aO:
The pointer is new.

bge CALL C0PY; Old space cmp, I HEAP BOTTOM,
bge OK move, b 4d' (ao), dO; Read tag cmpi, w FORWARDED, do
; Has it been moved? bne CALL CO
PYmove, 1 (ao), l1d (fp)
；Boy bra to the new space OK
CALL C0PY with data as an argument:
set moveq, b ttd, dO; set argument position jsr C0PY ROUTINE
;Go to movement processing routine 0: move, 1 1d(fp), ao;d(f
p) indicates the new space move, 1 (ao), aO.

Therefore, when the pointer points to data in the new space, the number of locks to be executed is 96 and the amount of code is 64 bytes, which is approximately 3.4 times faster and 11 times faster than garbage collection. This will result in an increase in the amount of code.

As described above, real-time garbage collection enables real-time processing for symbolic processing programs, but has the problem of reducing processing speed and increasing the amount of code due to overhead.

The present invention solves these conventional problems,
The purpose of the present invention is to provide a real-time garbage collection support device that can suppress overhead and enable high-speed processing.

[Means for solving problems]

FIG. 1 is a block diagram of the principle of a real-time garbage collection support device according to the present invention. The device of the present invention implements a part of the real-time garbage collection method, which was conventionally implemented using software, using hardware.

In the figure, data storage space detection means 101 checks whether an input argument points to a new space or an old space at the entrance of a built-in function or predicate.

The data movement state detection means 103 checks whether the data referenced by the program is data that has been moved to a new space or data that has not yet been moved.

The control means 105 is connected to the outputs of the data storage space detection means 101 and the data movement state detection means 103, and sends an interrupt request signal line 333 to the central processing unit when each output indicates the old space or before movement. An interrupt request signal for data movement is sent via the

[For production]

The present invention uses hardware to detect the storage space position of data in a storage area and the state of data movement from the old space to the new space.

That is, the data storage space detection means 101 compares the written pointer with the address value of the new space in the storage area, and determines whether it points to the old space or the new space. If the data is in the old space, the data movement state detection means 103 determines whether the data has been moved to the new space or before movement by comparing reference pointer tags. to decide.

By implementing these judgments and interrupt requests to the central processing unit using hardware, real-time garbage collection can be performed at high speed and the size of the program code can be made compact.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a block diagram showing the configuration of an embodiment of the real-time garbage collection system of the present invention.

FIG. 3 is a flowchart illustrating the operation of the embodiment of the present invention.

■、-乍41I! Correspondence between the embodiment of the present invention and FIG. 1 Here, the correspondence between the embodiment of the present invention and FIG. 1 will be shown.

The data storage space detection means 101 includes an external register 201
, 202, 203, comparators 204, 205, and AND circuit 206.

The data movement state detection means 103 includes an external register 211
, corresponds to the new space reference pointer tag value register 212 and the comparator 213.

The control means i05 corresponds to the control circuit 221.

↓ - 1 Large Plate ■ Wandering An example of the present invention will be described below, assuming that there is a correspondence relationship as described above.

In FIG. 2, a central processing unit (CPU) 310 and a main memory 320 are connected via an address bus 331 and a data bus 332, and between the address bus 331 and the data bus 332, the real-time garbage collection of the present invention is performed. The support device (indicated by a dashed line) is connected.

The address bus 331 includes external registers 201, 202.
203 and 211 are connected, and external registers 211, 201, 202 and 203 are connected in cascade to the data bus 332. Each output of external registers 201 and 202 is output to comparator 2.
04, and each output of the external registers 202 and 203 is connected to a comparator 205. Each output of the comparators 204 and 205 is connected to the control circuit 221 via an AND circuit 206. The outputs of the external register 211 and the new space reference pointer tag value register 212 are connected to a comparator 213, and the output of the comparator 213 is connected to the control circuit 221. The output of the control circuit 221 is connected to the central processing unit 310 via an interrupt request signal line 333.

Hereinafter, the operation of the embodiment of the present invention will be explained using the flowcharts shown in FIGS. 2 and 3.

The start address of the storage area corresponding to the current new space is written to the external register 201, and the end address thereof is written to the external register 203. When a manual argument needs to be checked due to the number of built-in functions or predicates, the argument is stored in the external register 202. Comparators 204 and 205 operate at this timing. Comparators 204 and 205 are comparators that check whether one of two inputs is larger (or smaller) than the other.

For example, the comparator 204 outputs "1" when the pointer written in the external register 202 is smaller than the starting address written in the external register 201. Comparator 205 outputs "1" when the pointer written to external register 202 is greater than the end address written to external register 203. Therefore, if this pointer is between the start address and end address, the output of the AND circuit 206 will be "1". That is, when the control circuit 2210 input is "1", the argument pointer points to a new space, and no interrupt is generated to the central processing unit 310 when writing to the external register 202.

If the argument pointer points to the old space, control circuit 2
21 generates an appropriate interrupt request signal from the output (rob) of the AND circuit 206, and issues an interrupt to the central processing unit 310 via an interrupt request signal line 333.

In response to this interrupt request No. 13, the processing of the central processing unit 310 instantly starts the processing routine for garbage collection (
Move to INTI). This routine uses the external register 20
The data in the old space pointed to by 2 is read out and placed in the external register 211. Comparator 213 operates at this timing.

The comparator 213 compares the value of the external register 211 and the new space reference pointer tag value register 212 that holds the immediate value of the tag to indicate that data has been moved by garbage collection.

If they are equal, it means that the data has been moved to the new space, and if they are not equal, it means that the data has not been moved.

Thereby, it is determined whether the data in the data movement process has been moved to the new space by garbage collection.

If it has not been moved, a signal is transmitted to the control circuit 221. When this signal is input, the control circuit 221 generates an appropriate interrupt request signal and issues an interrupt to the central processing unit 310 via the interrupt request signal line 333.

In the central processing unit 333, a data movement processing routine (COPY ROUTINE) is instantaneously activated by this interrupt request signal. This data movement processing routine moves data and stores the movement destination address in the external register 22.
1 and control returns to the processing routine (INTI).

If it has already been moved, no interrupt will be generated.

In the processing routine (INTI), the following command reads the contents of the external register 211 (data movement destination address),
Write to external register 202.

Control then returns to the CAR routine.

Therefore, a pointer pointing to the data in the new space is correctly set in the external register 202 at this point.

The code in this case is: CAR: move, 1 #d(fd), EXREG3move,
I EXREG3. a.

move, 1 (ao), aO INTI: move, I EXREG3. aO move, 1 (ao), EXREGImove, I
EXREGI, aO move, l ao, EXREG3 ts. However, the address of external register 211 is
REGI and the address of external register 202 as EXR.
IEG3.

When the device of the present invention is used, the number of locks executed by the function CAR is 56 when the argument pointer points to data in a new space, which is approximately 58 compared to an implementation example (96) that does not use the device of the present invention. It has been shortened to %. Further, even when compared with the case (28) using -discard type garbage collection, the reduction in processing speed can be suppressed to twice (3.4 times in the conventional case).

Furthermore, the amount of code when the program is compiled (
When using the device of the present invention, the object size is 30 bytes, which is less than half that of the conventional implementation example (64 hides). Bytes), the increase can be suppressed to 5 times (compared to 11 times in the past).

l-λKaihehen ■Dish-like.In addition, the ratio of the above-mentioned embodiments of the present invention l2RS 204
.

205 and the AND circuit 206 are connected to the external register 202
The pointer stored in the pointer is stored in the external register 201 and the external register 203.

This is a configuration for detecting whether or not there is a computer in the computer, and the configuration is not limited to this.

Further, the comparators 204 and 205 are configured to detect the magnitude of the two-person force, and the comparator 213 is configured to detect that the two-person force is equal.
This can be easily realized by using known technology in conjunction with 1.

〔Effect of the invention〕

As described above, according to the present invention, conditional judgment during execution of a symbolic processing program can be simplified to load and store instructions to external registers, thereby reducing processing time overhead and code amount overhead during compilation. , it has the effect of being able to significantly reduce it compared to the conventional technology.

Therefore, it is possible to realize real-time garbage collection with high speed and high object efficiency, which is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a block diagram showing the configuration of an embodiment of the invention, Fig. 3 is a flowchart explaining the operation of the embodiment of the invention, and Fig. 4 is based on the copy method. Figure 5 is a diagram explaining the batch garbage collection method, Figure 5 is a diagram explaining the real-time garbage collection method using Paker's algorithm, Figure 6 is a diagram showing an implementation example for a processing system with batch garbage collection, FIG. 7 is a diagram showing an implementation example based on Payker's algorithm. In the figure, 101 is a data storage space detection means, 103 is a data movement state detection means, 105 is a control means, 201 to 203.211 are external registers, and 204.20
5, 213 is a comparator, 206 is an AND circuit, 212 is a new space reference pointer tag value register, 221 is a control circuit, 310 is a central processing unit, 320 is a main storage device, 331 is an address bus, 332 is a data bus, 333 is an interrupt request signal line, 410.510 is the old space, and 420.520 is the new space. , 332 Day 7 Mold Power゛-■ Shiko and 7th Nump T Run I: January 14 Figure 5

Claims (1)

[Claims] In a real-time garbage collection method in which execution of a symbolic processing program and garbage collection are performed alternately, the a data storage space detection means (101) for checking whether an input argument points to a new space or an old space in the storage area; and a data storage space detection means (101) connected to the address bus (331). a data movement state detection means (103) connected to the data bus (332) via a data bus (332) and checking whether the data referenced by the program is data that has been moved to the new space or data that has not yet been moved; , the outputs of the data storage space detection means (101) and the data movement state detection means (103) are taken in, and when each output indicates the old space or before movement, an interrupt request signal line (333) is sent to the central processing unit. 1. A real-time garbage collection support device comprising: a control means (105) for making an interrupt request for data movement via a controller (105).