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1. (WO2019046268) CACHE LINE DATA
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CACHE LINE DATA

Technical Field

[0001] The present disclosure relates generally to memory devices, and more particularly, to method and apparatuses of memory system with cache line data.

Background

[0002] Memory devices are typically provided as internal,

semiconductor, integrated circuits in computing devices or other electronic devices. There are many different types of memory including volatile and nonvolatile memory. Volatile memory can require power to maintain its data (e.g., user data, error data, etc.) and includes random-access memory (RAM), dynamic random access memory (DRAM), and synchronous dynamic random access memory (SDRAM), among others. Non-volatile memory can provide persistent data by retaining stored data when not powered and can include NAND flash memory, NOR flash memory, read only memory (ROM), Electrically Erasable Programmable ROM (EEPROM), Erasable Programmable ROM (EPROM), and resistance variable memory such as phase change random access memory (PCRAM), resistive random access memory (RRAM), and magnet oresi stive random access memory (MRAM), among others.

[0003] A memory system can include a cache memory that may be smaller and/or faster than other memory of the system (e.g., DRAM, NAND, disk storage, solid state drives (SSD), etc., which may be referred to as main memory). As an example, cache memory may comprise DRAM memory. A memory system can cache data to improve performance of the memory system. Therefore providing cache memory that delivers improved performance for the memory system is desirable. Improving the latency and hit rate of the cache memory are performance characteristics that can provide improved performance of the memory system.

Brief Description of the Drawings

[0004] Figure 1 is a block diagram of a computing system including an apparatus in the form of a host and an apparatus in the form of memory system in accordance with one or more embodiments of the present disclosure.

[0005] Figure 2 is a block diagram of an apparatus in the form of a memory system in accordance with a number of embodiments of the present disclosure,

[0006] Figure 3 is a block diagram of an apparatus in the form of a cache including a number of cache lines in accordance with a number of embodiments of the present disclosure.

[0007] Figure 4 is a diagram of a cache line in accordance with a number of embodiments of the present disclosure.

Detailed Description

[0008] The present disclosure includes apparatuses and methods related to a memory system with cache line data. An example apparatus can store data in a number of cache lines in the cache, wherein each of the number of lines includes a number of chunks of data that are individually accessible.

[0009] In a number of embodiments, a cache line (e.g., cache entry) can include metadata, chunk metadata, tag information, and a number of chunks of data. The cache can be managed on a cache line level. For example, data transfer action determinations are made on the cache line and/or chunk level. A buffer on a cache controller can include address data and/or metadata associated with the data in the cache. The cache controller can use the address data and/or metadata in the buffer to manage the cache. The data in a cache line can be managed on the chunk level. For example, chunks of data in a cache line can be read and/or written to a cache line to service a request. The cache lines can include chunk metadata and chunks of data and the cache controller can manage the cache lines on the chunk level. For example, the cache controller can read, write, write-back, and/or fetch, among other operations, a portion of a cache line that includes a number of chunks of data that is less than a total amount of data on a cache line. Also, a cache line can be considered evicted once each of the dirty chunks of data on the cache line have been written back to the backing store in one or more operations.

[0010] In a number of embodiments, a cache line can be configured to store 4KB of data in 32 128B chunks, for example. Embodiments are not limited to particular cache line and/or chunk sizes can include cache lines of any size and chunks of any size, A cache controller can manage the 4KB of data in a

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cache line that corresponds to 4KB of data at a particular location in a memory device (e.g., backing store). The 32 128B chunks of data in the 4KB cache line can be accessed on an individual chunk level such that each chunk can be read and/or written when servicing requests.

[0011] The cache controller can access a number of chunks of data in a cache line of the cache in response to receiving a request for data (e.g., to read and/or write data to the cache). The cache controller can manage the request using a buffer on the cache controller and the cache controller can sendee the request by returning a portion of the number of chunks of data in the cache line corresponding to the request. The cache controller can be configured to issue commands to cause the cache to return the portion of the number of chunks of data corresponding to the request that were in the cache line when the request was received in response to cache controller determining the request is a hit. The cache controller can determine whether data corresponding to a request is a hit or a miss by using metadata for the cache that is stored in a buffer (e.g., SRAM, among other type of memory) on the cache controller.

[0012] In a number of embodiments, the cache controller issue commands to cause the cache to retrieve a portion of the number of chunks of data corresponding to the request from the memory device in response to cache controller determining the request is a miss. The cache controller can be configured to issue commands to cause the cache to, in response to determining the request is a miss, write dirty chunks of data in the cache line to the memory device that were in the cache line when the request was received. The cache controller is configured to issue commands to cause the cache to, in response to determining the request is a miss, select the cache line based upon the cache line having fewer dirty chunks than other cache lines in the cache.

[0013] The cache controller can be configured to issue commands to cause the cache to, in response to determining the request is a hit, write dirty chunks of data in the cache line to the memory device. The cache controller can be configured to issue commands to cause the cache to, in response to determining the request is a hit, replace chunks of data in the cache line that are not associated with the request and were invalid when the request was received, [0014] The cache controller can prioritize particular chunks of data that will not be evicted from the cache lines. The chunks of data can be prioritized based on how often the data will be accessed and/or the type of data. The cache controller can write the chunks of data from the memory device to the cache prior to receiving a request for the chunks of data (e.g., pre-fetch). Chunks of data from a portion of a memory device can be pre-fetched and stored in the cache to at least partially fill a cache line that corresponds to the portion of the memory device.

[0015] In a number of embodiments, the cache controller can write dirty chunks of data to the memory device when not servicing commands. Also, the cache controller can select chunks of data to remain in the cache based on a command from the host. The host can identify portions of data that it would like to have in the cache and the cache controller can pin those portions of data in the cache so that they are never evicted from the cache.

[0016] In the following detailed description of the present disclosure, reference is made to the accompanying drawings that form a pari hereof, and in which is shown by way of illustration how one or more embodiments of the disclosure may be practiced. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to practice the embodiments of this disclosure, and it is to be understood that other embodiments may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the present disclosure. As used herein, the designators "M", "N", and "X", particularly with respect to reference numerals in the drawings, indicates that a number of the particular feature so designated can be included. As used herein, "a number of a particular thing can refer to one or more of such things (e.g., a number of memory devices can refer to one or more memory devices).

[0017] The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example, 120 may reference element "20" in Figure 1, and a similar element may be referenced as 220 in Figure 2. As will be appreciated, elements shown in the various embodiments herein can be added, exchanged, and/or eliminated so as to provide a number of additional embodiments of the present disclosure.

[0018] Figure 1 is a functional block diagram of a computing system 100 including an apparatus in the form of a host 102 and an apparatus in the form of memory system 104, in accordance with one or more embodiments of the present disclosure. As used herein, an "apparatus" can refer to, but is not limited to, any of a variety of structures or combinations of structures, such as a circuit or circuitry, a die or dice, a module or modules, a device or devices, or a system or systems, for example. In the embodiment illustrated in Figure 1 A, memory system 104 can include a controller 108, a cache controller 120, cache 110, and a number of memory devices 1 1 1-1, . . ., 11 1-X. The cache 120 and/or memory devices 111-1, . . ., 1 -X can include volatile memory and/or non-volatile memory.

[0019] As illustrated in Figure 1 , host 02 can be coupled to the memory system 104. In a number of embodiments, memory system 104 can be coupled to host 102 via a channel. Host 102 can be a laptop computer, personal computers, digital camera, digital recording and playback device, mobile telephone, PDA, memory card reader, interface hub, among other host systems, and can include a memory access device, e.g., a processor. One of ordinary skill in the art will appreciate that "a processor" can intend one or more processors, such as a parallel processing system, a number of coprocessors, etc.

[0020] Host 102 can includes a host controller to communicate with memor system 104. The host 102 can send commands to the memor system 104 via a channel. The host 102 can communicate with memory system 104 and/or the controller 08 on memory system 04 to read, write, and erase data, among other operations. A physical host interface can provide an interface for passing control, address, data, and other signals between the memory system 104 and host 02 having compatible receptors for the physical host interface. The signals can be communicated between host 102 and memory system 104 on a number of buses, such as a data bus and/or an address bus, for example, via channels.

[0021] Controller 108, a host controller, a controller on cache 1 10, and/or a controller on can include control circuitry, e.g., hardware, firmware, and/or software. In one or more embodiments, controller 108, a host controller, a controller on cache 110, and/or a controller can be an application specific integrated circuit (ASIC) coupled to a printed circuit board including a physical interface. Memory system can include cache controller 120 and cache 110. Cache controller 120 and cache 1 10 can be used to buffer and/or cache data that is used during execution of read commands and/or write commands,

[0022] Cache controller 120 can include buffer 122. Buffer 122 can include a number of arrays of volatile memory (e.g., SRAM). Buffer 122 can be configured to store signals, address signals (e.g., read and/or write commands), and/or data (e.g., metadata and/or write data). The buffer 122 can temporarily store signals and/or data while commands are executed. Cache 110 can include arrays of memory cell s (e.g., DRAM memory cells) that are used as cache and can be configured to store data that is also stored in a memory device. The data stored in cache and in the memory device is addressed by the controller and can be located in cache and/or the memory device during execution of a command.

[0023] Memory devices 1 1 1-1, . . ., 111-X can provide main memory for the memory system or could be used as additional memory or storage throughout the memory system 104. Each memory device 111-1, . . ., 111-X can include one or more arrays of memory cells, e.g., non-volatile and/or volatile memory ceils. The arrays can be flash arrays with a NAND architecture, for example. Embodiments are not limi ted to a particul ar type of memory device. For instance, the memory device can include RAM, ROM:, DRAM, SDRAM, PCRAM, RRAM, and flash memory, among others.

[0024] The embodiment of Figure 1 can include additional circuitry that is not illustrated so as not to obscure embodiments of the present disclosure. For example, the memory system 104 can include address circuitry to latch address signals provided over TO connections through I/O circuitry. Address signals can be received and decoded by a row decoder and a column decoder to access the memory devices 1 11-1, . . ., 11 -X. It will be appreciated by those skilled in the art that the number of address input connections can depend on the density and architecture of the memory devices 111-1 , . . ., 111-X.

[0025] Figure 2 is a block diagram of an apparatus in the form of a memory system in accordance with a number of embodiments of the present disclosure. In Figure 2, the memory system can be configured to cache data and service requests from a host and/or memory system controller. The memory system can include cache controller 220 with buffer 222. Buffer 222 can include SRAM memory, for example. Buffer 222 can include information about the data

in cache 210, including metadata and/or address information for the data in the cache. The memory system can include a memory device 21 1 coupled to the cache controller 220. Memory device 21 1 can include non-volatile memory arrays and/or volatile memory arrays and can serve as the backing store for the memory system,

[0026] Cache controller 220, cache 210, and/or memory device 21 1 can each include a controller and/or control circuitry (e.g., hardware, firmware, and/or software) which can be used to execute commands on the cache controller 220, cache 210, and/or memory device 211. The control circuitry can receive commands from a host controller, a memory system controller, and/or cache controller 220. The control circuitry can be configured to execute commands to read and/or write data in the memory device 2 1 ,

[0027] Figure 3 is a block diagram of an apparatus in the form of a cache including a number of cache lines in accordance with a number of embodiments of the present disclosure. In Figure 3, cache 310 can include a number of cache entries, such as cache lines 330-1, ... , 330-N. The cache lines 330-1, ... , 330-N can include metadata 332- 1 , .. , 332-N, chunk metadata 332-1 , .. , 332-N, tag data 336-1, . . . , 336-N, and a number of chunks of data 338-1-1, ... , 338-M-N. Each cache line 330-1 , ... , 330-N can include metadata 332-1, .. , 332-N for a corresponding cache line. The metadata 332-1, ...332-N can also be stored in a buffer (e.g., buffer 122 in Figure 1) and used by the cache controller to manage the cache. For example, the metadata 332-1, ...332-N can be used and updated by the cache controller to make hit/miss determinations for requests from the host.

[0028] Each cache line can include chunk metadata 332-1 , . . .332-N for a corresponding cache line. Chunk metadata 332-1, ...332-N can be used to execute commands. For example, a request for a portion of data on a cache line can be serviced by using the chunk metadata 332-1, .. , 332-N to determine if the portion of data in the request is valid and/or dirty, to determine the location of the portion of data in the cache line, and/or to retrieve the portion of data from the cache line. The cache controller can access the chuck metadata 332-1, .. , 332-N for servicing a request to read and/or write data to the cache,

[0029] Each cache line can include chunks of data 338-1-1, ... , 338-M-N for a corresponding cache line. Chunks of data chunks of data 338-1-1, ... , 338- "7

M-N can be accessed on a chunk by chunk basis by the cache controller when servicing a request. Each chunk of data 338-1-1, ... , 338-M-N can include 128B of data and a cache line can include 128 chunks to store 4KB of data, for example.

[0030] Figure 4 is a diagram of a cache line in accordance with a number of embodiments of the present disclosure. The cache line 430 can include metadata 432, chunk metadata 434, tag data 436, and a number of chunks of data 438-1 438-N.

[0031] The cache controller can access the chunks of data 438-1 ... ,

438-N in cache line 430 in response to receiving a request for data (e.g., to read and/or write data to the cache). A portion of number of chunks of data 438-1 438-N corresponding to a request that were in the cache line when a request was received can be read and returned to the cache controller and/or host. For example, a request for data can be serviced by returning chunks of 438-2, 438-3, 438-4, and 438-5. A cache controller can determine whether chunks of data 438-1 ... , 438-N correspond to a request by using metadata for the cache that is stored in the buffer on the cache controller.

[0032] In a number of embodiments, the cache can write a portion of chunks of data 438-1 ... , 438-N that are dirty. Also, when selecting a cache line to evict from the cache, a cache line with the fewest dirty chunks can be selected so that fewer chunks of data are written to the memory device when evicting a cache line from the cache.

[0033] The cache controller issue commands to cause the cache to, in response to determining the request is a hit, write dirty chunks of data in the cache line to the memory device. The cache controller can issue commands to cause the cache to, in response to determining the request is a hit, replace chunks of data in the cache line that are not associated with the request and were invalid when the request was received.

[0034] The cache controller can pri oritize particular chunks of data that will not be evicted from the cache lines. The chunks of data can be prioritized based on how often the data will be accessed and/or the type of data. The cache controller can write the chunks of data from the memory device to the cache prior to receiving a request for the chunks of data (e.g., pre-fetch). Chunks of data from a portion of a memory device can be pre-f etched and stored in the

cache to at least partially fill a cache line that corresponds to the portion of the memory device.

[0035] In a number of embodiments, the cache controller can write dirty chunks of data to the memory device when not servicing commands. Also, the cache controller can select chunks of data to remain in the cache based on a command from the host. The host can identify portions of data that it would like to have in the cache and the cache controller can pin those portions of data in the cache so that they are never evicted from the cache.

[0036] Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art will appreciate that an arrangement calculated to achieve the same results can be substituted for the specific embodiments shown. This disclosure is intended to cover adaptations or variations of various embodiments of the present disclosure. It is to be understood that the above description has been made in an illustrative fashion, and not a restrictive one. Combination of the above embodiments, and other embodiments not specifically described herein will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments of the present disclosure includes other applications in which the above structures and methods are used. Therefore, the scope of various embodiments of the present discl osure should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.

[0037] In the foregoing Detailed Description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as refl ecting an intention that the disclosed embodiments of the present disclosure have to use more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.