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Dynamic hash table operation method based on hybrid DRAM-NVM memory

A DRAM-NVM, dynamic hash table technology, applied in the field of computer data storage, can solve the problem of high access delay, reduce access delay, optimize read and write performance, and reduce overhead.

Active Publication Date: 2020-07-28
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The present invention provides a dynamic hash table operation method based on hybrid DRAM-NVM memory. On the premise that the data can be recovered when the system crashes, the existing hash table operation method solves the problem of placing the directory on the critical path in the slow The technical problem of high access delay caused by high-speed NVM

Method used

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  • Dynamic hash table operation method based on hybrid DRAM-NVM memory
  • Dynamic hash table operation method based on hybrid DRAM-NVM memory
  • Dynamic hash table operation method based on hybrid DRAM-NVM memory

Examples

Experimental program
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Effect test

Embodiment 1

[0047] A segment split operation method based on the dynamic hash table of hybrid DRAM-NVM memory, such as figure 2 As shown, in this embodiment, n=256, and m can be any positive integer, and m is set to 0 for convenience of explanation; wherein, n represents the last n bits of the hash value, and m represents that the backup area occupies m buckets. Specifically, when the hash collision cannot be resolved, the capacity of the hash table needs to be expanded. There are two cases of segment splitting, among them, the first case, such as figure 2 As shown in section 3 in (a), if it is found that the local depth 2 of section 3 is less than the global depth 3 of the directory, it indicates that there is excess directory space. At this time, it is directly necessary to split the section and create a new section 4. Recalculate the hash values ​​of all hash elements in segment 3, migrate the hash elements with hash value prefix 101 in segment 3 to segment 4, modify the segment add...

Embodiment 2

[0049] A kind of insertion operation method based on the dynamic hash table of mixed DRAM-NVM memory, comprises the following steps:

[0050] For the element to be inserted , where key represents the key value of the storage element, and value represents the value of the storage element;

[0051] 2.1) For the element to be inserted, where key represents the key value of the storage element, and value represents the value of the storage element; the hash value of the key is calculated by the hash function, and the first k bits of the hash value correspond to Take out the segment address p1 from the array structure directory, and then obtain the corresponding bucket address p2 through the index of the last n digits of the hash value; where k and n are positive integers;

[0052] 2.2) Determine whether the hash unit in p1 is empty or whether the hash value of the key does not match the current index, if so, go to step 2.3), otherwise, go to step 2.4);

[0053] 2.3) Split the ke...

Embodiment 3

[0063] A kind of query operation method based on the dynamic hash table of mixed DRAM-NVM memory, comprises the following steps:

[0064] For the target element to be queried , where key represents the key value of the storage element, and value represents the value of the storage element; the segment address p1 and the bucket address p2 corresponding to the key of the target element to be queried are calculated through a hash function, Determine whether the current position is the target element, if so, return the value of the target element; otherwise, traverse the 4 consecutive buckets after p2 and the backup area p3 until the target element is found, and return its value, if there is still no value after traversing all the shared areas If the target element is found, the queried target element is not in the hash table.

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Abstract

The invention discloses a dynamic hash table operation method based on a hybrid DRAM-NVM (Dynamic Random Access Memory-Non-Volatile Memory). The method comprises a segment splitting operation, an insertion operation, a query operation, a deletion operation and a recovery operation, the method comprises the following steps: storing an array structure directory for storing a segment address of a hash unit in a dynamic hash table on a DRAM (Dynamic Random Access Memory), and storing a cardinal number tree structure directory for synchronously backing up the array structure directory in the dynamic hash table on an NVM (Non-Volatile Memory) to persist the array structure directory, so that the array structure directory is reconstructed after a system crashes; storing the hash units by adoptinga multi-layer structure, and storing the hash units on the NVM; according to the method, a cross storage key value pair and an atomic segment splitting mechanism are adopted to ensure the consistencyof data, the provided hash table fully utilizes the advantages of a hybrid memory, the expenditure of data consistency is relatively small, and the access delay is very low.

Description

technical field [0001] The invention belongs to the field of computer data storage, and more specifically relates to a method for operating a dynamic hash table based on a hybrid DRAM-NVM memory. Background technique [0002] In recent years, some new non-volatile memory (Non-Volatile Memory, NVM) technologies have begun to emerge, such as phase change memory (phaseChange Memory, PCM), memristor (ReRAM), spin torque magnetic memory (STT-MRAM) and 3D-XPoint etc. NVM not only has the power-down non-volatility of traditional disks, but also has the characteristics of fast memory access and byte-based addressing of DRAM. These excellent characteristics make it possible to replace DRAM as main memory. However, the current NVM technology still has shortcomings such as asymmetric read and write delays and limited wear times, and is more suitable for connecting with DRAM on the memory bus to form a hybrid memory. [0003] Changes in computer memory media and architecture have mad...

Claims

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Application Information

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IPC IPC(8): G06F12/02
CPCG06F12/0292
Inventor 王芳冯丹邹晓敏刘超杰
Owner HUAZHONG UNIV OF SCI & TECH
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