CN100508060C - Refresh method and device for random access memory - Google Patents

Abstract

The invention discloses a refresh method for random memorizer that it previously sets the mapping relation of the access intensity, refresh interval and refresh times. It includes: A. calculating the access intensity, determining the refresh interval and refresh times according to the access intensity and said mapping relation, controlling the refresh of random memorizer according to the refresh interval and refresh times; B. executing the step A repeatedly until complete the defined refresh times in the defined time. Additionally, a refresh device for random memorizer is disclosed. The refresh method and device provided by the invention can and improve the access efficiency and reliability.

Description

Refresh method and device for random access memory

technical field

The invention relates to a random access memory, in particular to a method and device for refreshing the random access memory.

Background technique

Random access memory is an important part of the capacity data processing circuit. With the development of data processing technology, higher and higher requirements are put forward for the capacity and performance of random access memory. Taking synchronous dynamic random access memory (SDRAM) as an example, SDRAM has large capacity, fast read and write speed, supports burst read and write, and is relatively cheap, so it has been widely used. Especially the current mobile handheld devices, such as mobile phones, MP4, etc., rely more on SDRAM.

Random access memory is a volatile memory, so each address must be refreshed within a certain period, otherwise the data stored in these addresses may be lost. When refreshing, the refreshing device of the SDRAM sends a refreshing command to the SDRAM, and the SDRAM executes a refreshing operation according to the refreshing command. Taking the SDRAM that needs to be refreshed N times within T time as an example, there is a method in the prior art: at a certain fixed moment in each T time, such as the start time, continuously send N refresh commands to the SDRAM, and the SDRAM Perform N consecutive refreshes according to the refresh command. Since each refresh is not completed immediately, and SDRAM cannot be accessed when it is refreshed, it needs to wait until the end of the refresh process before it can be accessed, so in the first method, there will be a long period of time when SDRAM cannot be accessed. For devices with high access time requirements, it cannot meet the requirements.

For this reason, another method proposed is: at a certain fixed moment in each T/N period, such as the beginning moment, a refresh command is sent to SDRAM, and SDRAM performs a refresh according to the refresh command, that is, N times of refresh are evenly distributed to T time. In the second method, although the refresh time is evenly distributed, the access to the memory is usually uneven in practical applications, so the second method does not fully consider the access intensity. If within a period of time, If the access intensity is high, the refresh at this time will still affect the access efficiency and reduce the reliability of the access.

It can be seen that the existing refresh technologies all affect the access efficiency and reduce the reliability of the access.

Contents of the invention

In view of this, the present invention provides a random access memory refreshing method on the one hand, and provides a random access memory refreshing device on the other hand. Can improve access efficiency and reliability.

The refreshing method of the RAM provided by the present invention includes: pre-setting the mapping relationship between the access intensity, the refreshing interval, and the number of refreshing times, and the method includes:

A. Calculate the access density, determine the refresh interval and the number of refreshes according to the calculated access density and the set mapping relationship, and control the RAM to refresh according to the determined refresh interval and the number of refreshes;

B. Repeat step A until the specified number of refreshes required by the refresh request are completed within the specified time of the refresh request; if it is determined that the specified number of refreshes has not been completed within the set time critical value, then the random access memory is controlled within the remaining time of the specified time Complete the remaining number of refreshes.

Wherein, the controlling the random access memory to refresh according to the determined refresh interval and refresh times is: sending a refresh command to the random access memory according to the determined refresh interval and refresh times.

Wherein, the mapping relationship between the access intensity and the refresh interval and the refresh times includes: the mapping relationship between the range interval of the access intensity and the refresh interval and the refresh times.

Wherein, said controlling the random access memory to complete the refresh of the remaining times in the remaining time of the specified time is: sending the refresh command of the remaining times to the random access memory according to the minimum time interval required for each refresh; or according to each refresh within the remaining time Send the refresh commands for the remaining number of times to the random access memory at an average time interval of .

Wherein, the time threshold value is a preset static time threshold value.

The static time critical value is: set according to the minimum time interval required for each refresh and the specified number of times in the refresh request.

Wherein, the time critical value is a dynamically calculated time critical value;

And the time critical value of the dynamic calculation is: according to the change of the refresh time and the number of refresh times, dynamically calculate the remaining time within the specified time and the minimum remaining time required for the remaining times, if the dynamically calculated remaining time is greater than the remaining times The required minimum remaining time, and when the difference between the minimum remaining time and the minimum remaining time reaches the preset threshold value, the remaining time is temporarily used as the time critical value for refreshing within the specified time.

Wherein, the computing access intensity specifically includes:

Set the number of sampling clock cycles; record the number of clock cycles accessed by the random access memory within the number of sampling clock cycles; calculate the percentage of the number of clock cycles accessed by the random access memory to the number of sampling clock cycles to obtain the access intensity;

Alternatively, the calculating the access intensity according to the time of accessing the random access memory specifically includes:

Set the number of sampling clock cycles; record the number of idle clock cycles of the random access memory within the number of sampling clock cycles; calculate the percentage of the idle clock cycles of the random access memory to the number of sampling clock cycles to obtain the access density.

The refresh device of random access memory provided by the present invention includes: a refresh decision unit and a refresh control unit, wherein,

The refresh decision-making unit is used to store the mapping relationship between the access intensity and the refresh interval and the number of refresh times; calculate the access intensity, determine the refresh interval and the refresh number according to the calculated access intensity and the stored mapping relationship, and report to the refresh control unit Send a control command to refresh according to the refresh interval and the number of refreshes until the specified number of refreshes required by the refresh request are completed within the specified time of the refresh request. Complete the control command for the remaining number of refreshes within the remaining time;

The refresh control unit is used to receive the control command for refreshing according to the refresh interval and the number of refreshes from the refresh decision-making unit, and control the RAM to refresh according to the received control command; complete the remaining number of refreshes within the remaining time according to the received control command to control the RAM to complete the remaining number of refreshes within the remaining time.

Wherein, the refresh decision-making unit includes: a refresh policy storage module and a refresh policy determination module, wherein,

Refresh policy storage module, used to store the mapping relationship between access intensity, refresh interval, and refresh times, and provide it to the refresh policy determination module;

The refresh policy determination module is used to calculate the access density, determine the refresh interval and the number of refreshes according to the calculated access density and the mapping relationship from the refresh policy storage module, and send the refresh control unit to refresh according to the refresh interval and the number of refreshes The control command until the specified number of refreshes required by the refresh request is completed within the specified time of the refresh request; when it is determined that the specified number of refreshes has not been completed within the set time critical value, the refresh control unit is sent to the refresh control unit to complete the remaining number of refreshes within the remaining time control commands.

Preferably, the refresh policy determination module dynamically calculates the remaining time and the minimum remaining time required for the remaining times within the specified time according to the change of the refreshing time and the number of refreshing times, if the dynamically calculated remaining time is greater than the remaining times required When the minimum remaining time and the difference between the minimum remaining time and the minimum remaining time reach the preset threshold value, the remaining time is temporarily used as the time threshold for refreshing within the specified time, and it is determined that it is not completed within the set time threshold A specified number of refreshes;

Alternatively, the refresh policy determining module determines whether the specified number of refreshes are not completed within the set time critical value according to a preset time critical value stored in the refresh policy storage module.

Preferably, the refresh control unit includes: a main control module and a signal generation module, wherein,

The main control module is used to receive a control command for refreshing according to the refresh interval and refresh times from the refresh decision module, and send a refresh command generation instruction to the signal generation module according to the refresh interval and refresh times according to the received control command; The decision-making module completes the control command for the remaining number of refreshes within the remaining time, according to the received control command, sends the remaining number of refresh command generation instructions to the signal generation module according to the minimum time interval required for each refresh; or according to each refresh Send the refresh command generation instructions of the remaining number of times to the signal generation module at the average time interval in the remaining time;

The signal generating module is configured to generate an instruction according to the refresh command from the main control module, generate a refresh command, and send it to the RAM.

Wherein, the refresh device of the random access memory can be set in the controller of the random access memory, and the main control module in the device can be set in the controller unit in the random access memory controller, and the signal generation module in the device can be set In the control signal generator unit in the random access memory controller.

As can be seen from the above scheme, the present invention pre-sets the mapping relationship between access intensity, refresh interval, and number of refreshes; calculates the access intensity, and determines the refresh interval and the number of refreshes according to the calculated access intensity and the set mapping relationship, Refresh the random access memory according to the determined refresh interval and refresh times. In the present invention, the mapping relationship between access intensity, refresh interval and refresh times is set so that when access is intensive, the refresh interval is long and the number of refreshes is small; when access is sparse, the refresh interval is short and the number of refreshes is large, so that when access is intensive, The number of refreshes is reduced, and when the access is sparse, the number of refreshes is increased, thereby improving the efficiency and reliability of access while ensuring the refresh requirement.

Description of drawings

FIG. 1 is a flow chart of a method for refreshing a random access memory in an embodiment of the present invention.

FIG. 2 is a schematic structural diagram of a refresh device for random access memory in an embodiment of the present invention.

FIG. 3 is a schematic structural diagram of an example of a specific application of a RAM refresh device in an embodiment of the present invention.

Detailed ways

The basic idea of the present invention is: set the mapping relationship between the access intensity and the refresh interval and the number of refresh times; calculate the access intensity, determine the refresh interval and the refresh number according to the calculated access intensity and the set mapping relationship, and The refresh interval and the refresh times control the random access memory to refresh until the specified number of refreshes required by the refresh is completed within the specified time of the refresh requirement.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and accompanying drawings.

Random access memory generally has refresh requirements, that is, it is required to complete a specified number of refreshes within a specified time, for example, it is required to complete N times of refreshes within T time. Therefore, the basic idea of the present invention is to control the RAM to be refreshed according to the access intensity within each specified time, until the number of refreshes reaches the specified number of times within the specified time, and wait for the arrival of the next specified time.

In addition, in order to ensure that the specified number of refreshes are completed within the specified time, a time critical value can be set to control the RAM to complete the remaining number of refreshes within the remaining time when the specified number of refreshes is not completed when the time critical value is reached. After that, wait for the arrival of the next prescribed time.

Wherein, the calculation method of access density can be: preset the number of sampling clock cycles, record the number of clock cycles that the random access memory is accessed within the number of sampling clock cycles, and calculate the number of sampling clock cycles occupied by the number of clock cycles that the random access memory is accessed The percentage of access intensity is obtained.

Alternatively, the calculation method of the access density can also be: preset the number of sampling clock cycles, and record the number of clock cycles of the random access memory in the number of sampling clock cycles; Percentage to get access intensity.

The method for refreshing the random access memory in the present invention will be described in detail below in conjunction with specific embodiments.

In this embodiment, in order to ensure that a specified number of refreshes are completed within a specified time, a time critical value is set. And in this embodiment, the number of sampling clock cycles required for calculating the access density is preset.

Referring to FIG. 1 , FIG. 1 is a flowchart of a method for refreshing a random access memory in an embodiment of the present invention. The process includes the following steps:

Step 101, setting the mapping relationship between access intensity, refresh interval, and refresh times; setting the number of sampling clock cycles; and setting a time threshold.

The setting method of the mapping relationship between access intensity, refresh interval and refresh times is as follows:

According to refresh requirements and general access conditions or experience, set the mapping relationship between access intensity, refresh interval, and refresh times. When the access intensity is in a certain range, it can be refreshed according to a certain time interval (refresh interval) in the next time or several consecutive times (refresh times). For example, the mapping relationship table shown in Table 1 can be set:

The value of access intensity X refresh interval refresh times 0<X≤20 P1 N1 20<X≤40 P2 N2 40<X≤60 P3 N3 60<X≤80 P4 N4 80<X≤100 P5 N5

Table I

In Table 1, the access intensity is divided into 5 intervals, and each interval corresponds to a refresh interval value and a refresh count value. In practical applications, there can be many kinds of divisions of range intervals, and there can also be many kinds of values from P1 to P5 and N1 to N5. Specifically, the interval division and values can be carried out according to the actual situation. In this embodiment, only the values in Table 1 are used. The division and value selection of is given as an example.

In this embodiment, when the access intensity is in the interval (0, 20], the corresponding refresh interval is P1, and the number of refreshes is N1, that is, when the access intensity is in the interval (0, 20], refresh N1 times, and Each refresh interval is P1. Afterwards, the corresponding refresh is carried out according to the new access density and its refresh interval and refresh times. The relationship between other access densities in Table 1 and their refresh intervals and refresh times is the same. I won't repeat them here.

Wherein, the access density may be the actual access time density, or the actual idle time density.

The method of setting the number of sampling clock cycles is as follows:

The number of sampling clock cycles can be selected according to the actual situation. Taking an SDRAM that works at 100MHz and refreshes 4096 times within 64ms as an example, the specified time is 64ms and the specified number of times is 4096 times. According to the operating frequency and refresh requirements The average time interval for each refresh is calculated to be 1562 clock cycles. In this step, when setting the number of sampling clock cycles, it can be set to about one-tenth of the average time interval of each refresh. For example, 100 clock cycles can be selected as the number of sampling clock cycles; or, in practical applications, it can also be based on Empirical value, set the sampling clock period.

The method of setting the time threshold is as follows:

There are two methods for setting the time critical value. The first method is: set a static time critical value in advance. In order to ensure that the refresh requirements are completed within the specified time of the refresh requirement, the most conservative time threshold can be adopted. Value setting, that is, assuming that the access intensity is always high before reaching the time critical value, and no refresh is performed, all refresh times need to be completed in the remaining time after the critical value. Therefore, when setting, it can be set according to the minimum time interval required for each refresh, multiply the minimum time interval by the specified number of times to obtain the required minimum remaining time, and then subtract the minimum remaining time from the specified time to obtain the time critical value.

Still taking the SDRAM that works at 100MHz and refreshes 4096 times within 64ms as an example, assuming that the minimum time interval required for each refresh is 8 clock cycles, the minimum remaining time required for 4096 refreshes is 4096×8 = 32768 clock cycles, about 0.33ms, so the time threshold can be set to 64-0.33 = 63.67ms, in order to be more secure, the time threshold can be set to 63ms, or 62ms, etc., while ensuring smooth access, as long as It is enough to ensure that the remaining number of refreshes can be completed within the remaining time.

The second method for setting the time critical value is: dynamically set the time critical value, that is, as the refresh continues within the specified time, according to the change of the refresh time and the number of refreshes, dynamically calculate the minimum time required for the remaining time and the remaining times For the remaining time, when the remaining time is greater than or close to the minimum remaining time required for the remaining times, the remaining time is temporarily used as the time threshold for refreshing within the specified time. Further, a threshold value can also be set. When the dynamically calculated remaining time is greater than the minimum remaining time required for the remaining times, and the difference with the minimum remaining time reaches the set threshold value, the remaining time is temporarily used as The time threshold for refreshing within the specified time this time.

Of course, when the second method is used to set the time critical value, the calculation and setting of the time critical value are not completed in this step 101, but are dynamically calculated during the entire process operation, and are described in this step , just for comparison with the first method.

Step 102, calculate the access intensity, and determine the refresh interval and refresh times according to the access intensity and the mapping relationship set in step 101.

In this step, within the number of sampling clock cycles set in step 101, record the number of clock cycles that the random access memory is accessed, calculate the percentage of the number of clock cycles that are accessed to the number of sampling clock cycles, and obtain the access density; or by Within the number of sampling clock cycles, record the number of idle clock cycles of the random access memory, and calculate the percentage of the number of idle clock cycles occupied by the number of sampling clock cycles to obtain the access density. The specific calculation method can be determined according to the meaning of access intensity in Table 1.

After the access density is calculated, the refresh interval and refresh times are determined according to the calculated access density and the mapping relationship set in step 101 .

Step 103, controlling the random access memory to refresh according to the determined refresh interval and refresh times.

During specific implementation, a refresh command may be sent to the RAM according to the determined refresh interval and refresh times.

Step 104, judging whether the time critical value is reached, if not, execute step 105; otherwise, execute step 106.

If the time critical value is set by the first method described in step 101, it is sufficient to directly compare and judge with the set static time critical value in this step.

If the time threshold is set using the second method described in step 101, then in this step, it is necessary to judge whether the remaining time is greater than and close to the minimum remaining time required for the remaining number of times, and if so, then judge the reaching time critical value. Or the threshold value is set in advance, then in this step it is necessary to judge whether the remaining time is greater than the minimum remaining time required for the remaining times, and the difference with the minimum remaining time reaches the set threshold value, if so, then judge the reaching time critical value.

Step 105, judging whether the number of refresh times reaches the specified number, if yes, execute step 107; otherwise, return to execute step 102.

In step 106, it is judged whether the number of refresh times reaches the specified number, if yes, execute step 107; otherwise, execute step 108.

If the time threshold is set using the second method described in step 101, then in this step, it is not necessary to judge whether the number of refreshes reaches the specified number of times, but directly execute step 108.

In step 107, the refreshing within the specified time is ended, and then step 109 is continued.

Step 108 , controlling the random access memory to complete the remaining number of refreshes within the remaining time, and then proceed to step 109 .

In this step, if the time critical value set in step 101 is 63ms, and when it reaches 63ms, 4000 refreshes have been completed, then the RAM is controlled to complete the remaining 96 refreshes within the last 1ms.

During specific implementation, the remaining number of refresh commands may be sent to the RAM according to the minimum time interval required for each refresh. Still taking the minimum time interval required by the random access memory as 8 clock cycles as an example, at the beginning of the remaining time, a refresh command may be sent to the random access memory every 8 clock cycles according to the remaining number of times.

Or in specific implementation, the remaining times of refreshing commands are sent to the RAM according to the average time interval of each refreshing within the remaining time, that is, the remaining times are evenly distributed to the remaining time. Taking the remaining time as 1ms and the remaining times as 96 times as an example, 1ms is about 99968 clock cycles. For 96 times, the average time interval is 99968÷96=1041 clock cycles. To be on the safe side, the average The time interval can take a value less than 1041, such as 1000, etc., at the beginning of the remaining time, a refresh command can be sent to the random access memory every 1000 clock cycles according to the remaining number of times.

In the above two cases, the first refresh command can be sent at the beginning of the remaining time.

Step 109, judging whether the next specified time has arrived, and if so, return to step 102 for execution.

So far, this process ends.

In the process shown in FIG. 1 , there is no absolute sequence relationship between step 103 and step 104 , and the time of step 104 can be judged while step 103 is being executed.

Wherein, when the access density is calculated in step 102, it may be performed within the sampling clock cycle after completing the determined number of refreshes in step 103, or within the sampling clock cycle before the last refresh is performed. An example is as follows: If the preset number of sampling clock cycles is 100 clock cycles, the refresh interval determined this time is 1000 clock cycles, and the number of refreshes is 3, then when calculating the access density, you can calculate the access density within 100 clock cycles after the last refresh. It may be performed within a clock cycle, or it may be performed within 100 clock cycles before the last refresh is performed, that is, before the last refresh is performed, and the refresh interval is counted to 900 clocks.

The random access memory device based on the method shown in FIG. 1 will be described in detail below.

Referring to FIG. 2 , FIG. 2 is a schematic structural diagram of a refresh device for random access memory in an embodiment of the present invention. As shown in FIG. 2 , the device includes: a refresh decision unit 210 and a refresh control unit 220 .

Wherein, the refresh decision-making unit 210 is used to store the mapping relationship between the access intensity and the refresh interval and the number of refresh times; calculate the access intensity, determine the refresh interval and the refresh number according to the calculated access intensity and the stored mapping relationship, and provide The refresh control unit 220 sends a control command to perform refresh according to the refresh interval and the refresh times, until the refresh required for the specified number of times is completed within the specified time of the refresh request.

Wherein, the mapping relationship between the access intensity, the refresh interval and the refresh times can be configured in the refresh decision unit 210 by pre-configuring the refresh policy.

Refresh decision-making unit 210 can sample the access signal at a preset number of sampling cycles when performing access density calculations, record the number of clock cycles that the random access memory is accessed, and calculate the number of clock cycles that the access takes up 100% of the number of sampling clock cycles. Percentage to obtain the access density; or by recording the number of idle clock cycles of the random access memory within the preset number of sampling clock cycles, and calculating the percentage of the number of sampling clock cycles occupied by the idle clock cycles to obtain the access density. The specific calculation method to be used may be determined according to the meaning of the access intensity in the pre-configured mapping relationship.

The refresh control unit 220 is configured to receive a refresh control command from the refresh decision unit 210 according to the refresh interval and refresh times, and control the RAM to perform refresh according to the received control command.

As shown in FIG. 2 , during specific implementation, the refresh decision unit 210 may specifically include: a refresh policy storage module 211 and a refresh policy determination module 212 .

Wherein, the refresh policy storage module 211 is used to store the mapping relationship between access intensity, refresh interval, and refresh times, and provide it to the refresh policy determination module 212 .

The mapping relationship between the access intensity, the refresh interval, and the refresh times can be configured in the refresh policy storage module 211 by pre-configuring the refresh policy.

The refresh policy determination module 212 is used to calculate the access density, determine the refresh interval and the number of refreshes according to the calculated access density and the mapping relationship from the refresh policy storage module 211, and send to the refresh control unit 220 according to the refresh interval and refresh rate. Refresh the control command for the number of times until the specified number of refreshes required by the refresh is completed within the specified time for the refresh request.

Refresh policy determination module 212 can record the number of clock cycles accessed by the random access memory by sampling the access signal within the preset number of sampling cycles when calculating the access intensity, and calculate the number of clock cycles occupied by the access to the sampling clock cycle The access density is obtained as a percentage of the number; or the access density is obtained by recording the number of idle clock cycles of the RAM within the preset number of sampling clock cycles and calculating the percentage of the idle clock cycles occupying the number of sampling clock cycles. The specific calculation method to be used may be determined according to the meaning of the access intensity in the pre-configured mapping relationship.

Wherein, the refresh strategy storage module 211 and the refresh strategy determination module 212 can further be:

The refresh strategy storage module 211 is further configured to: store a preset time threshold and provide it to the refresh strategy determination module 212 .

The refresh policy determination module 212 is further configured to: obtain a time critical value from the refresh policy storage module 211, and when it is determined that the specified number of refreshes have not been completed within the time critical value, send to the refresh control unit 220 the completion of the remaining number of refreshes within the remaining time. control commands.

Then the refresh control unit 220 is further configured to: according to the received control command to complete the remaining number of refreshes within the remaining time, control the random access memory to complete the remaining number of refreshes within the remaining time.

Alternatively, the refresh policy storage module 211 and the refresh policy determination module 212 may further be:

The refresh policy storage module 211 is not used to store the preset time critical value, but the refresh policy determination module 212 is further used to: dynamically calculate the time according to the second method of setting the time critical value described in the process step 101 shown in FIG. 1 critical value, when it is determined that the specified number of refreshes have not been completed within the time critical value, a control command to complete the remaining number of refreshes within the remaining time is sent to the refresh control unit 220 .

Then the refresh control unit 220 is further configured to: according to the received control command to complete the remaining number of refreshes within the remaining time, control the random access memory to complete the remaining number of refreshes within the remaining time.

During specific implementation, the refresh control unit 220 may specifically include: a main control module 221 and a signal generation module 222 .

Wherein, the main control module 221 is configured to receive a control command for refreshing according to the refresh interval and refresh times from the refresh decision module 210, and send a refresh command to the signal generation module 222 according to the refresh interval and refresh times according to the received control command to generate instruction.

In addition, the main control module 211 is further configured to receive a control command from the refresh decision module 210 to complete the remaining times of refreshing within the remaining time, and continuously send the remaining times to the signal generating module 222 according to the received control command within the remaining time. The Refresh command generates instructions.

Wherein, continuously sending the remaining number of refresh command generation instructions to the signal generation module 222 may be: the main control module 211 sends the remaining number of refresh command generation instructions to the signal generation module 222 according to the minimum time interval required for each refresh; The module 211 sends the remaining number of refresh command generation instructions to the signal generation module 222 according to the average time interval of each refresh within the remaining time.

The signal generation module 222 is configured to generate a refresh command according to the refresh command generation instruction from the main control module 221 and send it to the RAM.

In practical applications, the random access memory refresh device can be set in the random access memory controller, as shown in FIG. 3 , which is a schematic structural diagram of the random access memory controller using the above random access memory refresh device. In the controller shown in Figure 3, the main control module 221 of the refresh control unit 220 of the device shown in Figure 2 is set in the controller unit 301 in the controller, and the signal generating module 222 is set in the control signal generation in the controller In the controller unit 302 , the refresh decision unit 210 is set as an independent unit. In addition, the controller also includes: a random access memory status register 303 and a data latch 304 .

Wherein, in addition to the function of the main control module 221, the controller unit 301 is also used to control the control signal generator unit 302 to send read and write data to the random access memory according to the access of the central processing unit and the state of the random access memory in the random access memory status register 303. The required control signals and the control data latch 304 latch the data that needs to be written into and read out of the random register, and at the same time perform existing operations such as the interaction of control information with the central processing unit, which will not be described in detail here. describe.

When the random access memory controller shown in Figure 3 is specifically implemented, the central processing unit can configure the refresh strategy in the refresh decision unit 210 in advance, including setting the mapping relationship between access intensity, refresh interval, and refresh times in the refresh strategy storage module 211 , and set the number of sampling clock cycles; set the time critical value, etc., for providing to the refresh strategy determination unit 212, then the refresh strategy determination unit 212 records the number of clock cycles that the random access memory is accessed within the set sampling clock cycle number, Calculate the percentage of the number of clock cycles occupied by the access to the number of sampling clock cycles to obtain the access density; or by recording the number of free clock cycles of the random access memory within the number of sampling clock cycles, calculate the number of sampling clock cycles occupied by the number of idle clock cycles The percentage of access intensity is obtained. The specific calculation method can be determined according to the meaning of access intensity in Table 1. Refresh policy determination unit 212 determines the refresh interval and refresh times according to the calculated access density and the preset mapping relationship, and sends to the controller unit 301 to refresh according to the refresh interval and refresh times according to the determined refresh interval and refresh times. The control command will stop sending until the specified number of refreshes requested by the refresh request are completed within the specified time of the refresh request; and when the next specified time arrives, the above functions will be repeatedly executed.

The controller unit 301 receives a control command for refreshing according to the refresh interval and refresh times from the refresh decision determination module 212, and sends a refresh command generation instruction to the control signal generator unit 302 according to the refresh interval and refresh times according to the received control command , the control signal generator unit 302 receives a refresh command generation instruction from the controller unit 301, generates a refresh command according to the received refresh command generation instruction, and sends it to the RAM.

Further, the refresh policy storage module 211 and the refresh policy determination module 212 in the refresh decision unit 210 in FIG. 3 may further be:

The refresh strategy storage module 211 is further configured to: store a preset time threshold and provide it to the refresh strategy determination module 212 .

The refresh policy determination module 212 is further configured to: obtain a time critical value from the refresh policy storage module 211, and when it is determined that the specified number of refreshes have not been completed within the time critical value, send to the refresh control unit 220 the completion of the remaining number of refreshes within the remaining time. control commands.

Alternatively, the refresh policy storage module 211 and the refresh policy determination module 212 in the refresh decision unit 210 in FIG. 3 may further be:

The refresh policy storage module 211 is not used to store the preset time critical value, but the refresh policy determination module 212 is further used to: dynamically calculate the time according to the second method of setting the time critical value described in the process step 101 shown in FIG. 1 critical value, when it is determined that the specified number of refreshes have not been completed within the time critical value, a control command to complete the remaining number of refreshes within the remaining time is sent to the refresh control unit 220 .

The controller unit 301 is further configured to receive a control command from the refresh decision module 210 to complete the remaining number of refreshes within the remaining time, and continuously send the remaining number of refreshes to the control signal generator unit 302 according to the received control command within the remaining time. The number of refresh command generation instructions.

Wherein, continuously sending the remaining number of refresh command generation instructions to the control signal generator unit 302 may be: the controller unit 301 sends the remaining number of refresh command generation instructions to the control signal generator unit 302 according to the minimum time interval required for each refresh or the controller unit 301 sends the remaining number of refresh command generation instructions to the control signal generator unit 302 according to the average time interval of each refresh within the remaining time.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (13)

1. A method for refreshing random access memory, characterized in that the mapping relationship between access density, refresh interval, and refresh times is preset, and the method includes: A. Calculate the access density, determine the refresh interval and the number of refreshes according to the calculated access density and the set mapping relationship, and control the RAM to refresh according to the determined refresh interval and the number of refreshes; B. Repeat step A until the specified number of refreshes required by the refresh request are completed within the specified time of the refresh request; if it is determined that the specified number of refreshes has not been completed within the set time critical value, then the random access memory is controlled within the remaining time of the specified time Complete the remaining number of refreshes. 2. The method according to claim 1, wherein the controlling the random access memory to refresh according to the determined refresh interval and refresh times is: sending a refresh command to the random access memory according to the determined refresh interval and refresh times. 3. The method according to claim 1, wherein the mapping relationship between the access intensity and the refresh interval and the refresh times comprises: the mapping relationship between the access intensity range and the refresh interval and the refresh times. 4. The method according to claim 1, wherein the controlling the random access memory to complete the remaining number of refreshes within the remaining time of the specified time is: sending the remaining number of refreshes to the random access memory according to the minimum time interval required for each refresh. refresh commands; or send the remaining number of refresh commands to the random access memory according to the average time interval of each refresh within the remaining time. 5. The method according to claim 1, wherein the time critical value is a preset static time critical value. 6. The method according to claim 5, wherein the static time critical value is set according to the minimum time interval required for each refresh and the specified number of refresh requests. 7. The method according to claim 1, wherein the time critical value is a dynamically calculated time critical value; And the time critical value of the dynamic calculation is: according to the change of the refresh time and the number of refresh times, dynamically calculate the remaining time within the specified time and the minimum remaining time required for the remaining times, if the dynamically calculated remaining time is greater than the remaining times The required minimum remaining time, and when the difference between the minimum remaining time and the minimum remaining time reaches the preset threshold value, the remaining time is temporarily used as the time critical value for refreshing within the specified time. 8. The method according to any one of claims 1 to 7, wherein the computing access intensity specifically includes: Set the number of sampling clock cycles; record the number of clock cycles accessed by the random access memory within the number of sampling clock cycles; calculate the percentage of the number of clock cycles accessed by the random access memory to the number of sampling clock cycles to obtain the access intensity; Alternatively, the calculating the access intensity according to the time of accessing the random access memory specifically includes: Set the number of sampling clock cycles; record the number of idle clock cycles of the random access memory within the number of sampling clock cycles; calculate the percentage of the idle clock cycles of the random access memory to the number of sampling clock cycles to obtain the access density. 9. A random access memory refresh device, characterized in that the device comprises: a refresh decision unit and a refresh control unit, wherein, The refresh decision-making unit is used to store the mapping relationship between the access intensity and the refresh interval and the number of refresh times; calculate the access intensity, determine the refresh interval and the refresh number according to the calculated access intensity and the stored mapping relationship, and report to the refresh control unit Send a control command to refresh according to the refresh interval and the number of refreshes until the specified number of refreshes required by the refresh request are completed within the specified time of the refresh request. Complete the control command for the remaining number of refreshes within the remaining time; The refresh control unit is used to receive the control command for refreshing according to the refresh interval and the number of refreshes from the refresh decision-making unit, and control the RAM to refresh according to the received control command; complete the remaining number of refreshes within the remaining time according to the received control command to control the RAM to complete the remaining number of refreshes within the remaining time. 10. The device according to claim 9, wherein the refresh decision unit comprises: a refresh policy storage module and a refresh policy determination module, wherein, Refresh policy storage module, used to store the mapping relationship between access intensity, refresh interval, and refresh times, and provide it to the refresh policy determination module; The refresh policy determination module is used to calculate the access density, determine the refresh interval and the number of refreshes according to the calculated access density and the mapping relationship from the refresh policy storage module, and send the refresh control unit to refresh according to the refresh interval and the number of refreshes The control command until the specified number of refreshes required by the refresh request is completed within the specified time of the refresh request; when it is determined that the specified number of refreshes has not been completed within the set time critical value, the refresh control unit is sent to the refresh control unit to complete the remaining number of refreshes within the remaining time control commands. 11. The device according to claim 10, wherein the refresh policy determining module dynamically calculates the minimum time required for the remaining time and the remaining times within the specified time period according to the change of the refresh time and the number of refresh times. Remaining time, if the dynamically calculated remaining time is greater than the minimum remaining time required for the remaining times, and the difference between the remaining time and the minimum remaining time reaches the preset threshold value, the remaining time is temporarily used as the refresh time within the specified time Critical value, and determine that the specified number of refreshes have not been completed within the set time critical value; Alternatively, the refresh policy determining module determines whether the specified number of refreshes are not completed within the set time critical value according to a preset time critical value stored in the refresh policy storage module. 12. The device according to claim 11, wherein the refresh control unit comprises: a main control module and a signal generation module, wherein, The main control module is used to receive a control command for refreshing according to the refresh interval and refresh times from the refresh decision module, and send a refresh command generation instruction to the signal generation module according to the refresh interval and refresh times according to the received control command; The decision-making module completes the control command for the remaining number of refreshes within the remaining time, according to the received control command, sends the remaining number of refresh command generation instructions to the signal generation module according to the minimum time interval required for each refresh; or according to each refresh Send the refresh command generation instructions of the remaining number of times to the signal generation module at the average time interval in the remaining time; The signal generating module is configured to generate an instruction according to the refresh command from the main control module, generate a refresh command, and send it to the RAM. 13. The device according to claim 12, characterized in that the device is set in a random access memory controller, and the main control module in the device is set in a controller unit in the random access memory controller, the The signal generation module in the device is set in the control signal generator unit in the random access memory controller.

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