CN104539533B - The method and its application of channel table are established according to each layer of TSV connection state in 3D NoC - Google Patents

Abstract

The invention discloses a method for establishing a channel table according to the TSV connection status of each layer in a 3D NoC and its application. The algorithm establishes the shortest circular path, and the channel table of each channel node records the addresses of the next upper channel node and lower channel node in the shortest circular path; the channel table of ordinary nodes records the nearest upper channel node and Down channel node address; a heterogeneous 3D NoC TSV fault-tolerant routing algorithm based on the upper and lower priority strategy uses the above channel table to obtain the available upper channel node or channel table of the current node when transmitting data packets between layers. The address of the next channel node, the data packet is sent to this address, and the data is transmitted through the channel node. The invention can realize effective data transmission in any scale heterogeneous 3D NoC, and has TSV fault tolerance and congestion relief functions.

Description

Method for establishing channel table according to TSV connection status of each layer in 3D NoC and its method application

technical field

The invention relates to a 3D NoC routing algorithm, more specifically an on-chip routing algorithm for heterogeneous 3D NoC structures, capable of fault tolerance to failed TSVs and relieving congestion of upper and lower channels.

Background technique

3D NoC (Three-Dimension Network-on-Chip) is an interconnection method that realizes vertical integration by interconnecting multi-layer wafers (die) through through-silicon vias (TSVs). It overcomes the limitation that all components in 2D-NoC are distributed on one plane, resulting in smaller size, better power consumption and RF performance. 3D-NoC has greatly improved the integration of chips through vertical integration, and is considered by most experts as a new method to continue the growth trend of Moore's Law, and has become one of the fastest-growing technologies in the current semiconductor industry.

Common 3D NoC topologies include 3D Mesh, 3D Torus, 3D stacked Mesh, etc. Among them, the structure widely studied by many scholars is 3D Mesh. The traditional 3D Mesh structure is a regular 3D network structure formed by stacking regular 2D NoC up and down, and each layer communicates between layers through TSV. These TSVs are actually a series of vertical conductions between wafers and wafers, which are used to realize the interconnection between chips. A TSV represents a data link used to transmit signals in the vertical direction.

The traditional 3D NoC router on chip is realized by extending the 2D router on chip. On the basis of the original 2D router on chip east, west, south, north and local 5 pairs of input and output ports, two pairs of upper and lower ports are added to realize the vertical direction interlayer communication. The routing algorithm among them realizes the data transmission by extending the routing algorithm in the traditional 2D NoC, for example, extending the traditional X-Y dimension order routing algorithm to the X-Y-Z routing algorithm, that is, the data packet is first transmitted in the layer to the same vertical direction as the destination node. The intermediate node of the position, and then vertically transmit to the destination node through TSV. In today's industrial design, modules that implement different functions are usually placed on different layers of the 3D chip, for example, the CPU core is placed on the top layer, RAM and ROM are placed on the middle layer, and communication modules are placed on the bottom layer. Such a design makes it difficult to achieve a consistent layout of network nodes on each layer, resulting in some routing nodes having upward or downward channels, that is, connected with TSVs, while some nodes have no vertical channels. Such a structure makes it difficult to use traditional 3D routing algorithms to achieve the purpose of transmitting data packets.

Nowadays, the chip manufacturing process has entered below 65 nanometer level, the manufacturing process is becoming more and more complex, and the manufacturing difficulty is becoming more and more difficult. The size of TSV is only about 10 microns, but the current TSV manufacturing technology is not mature enough, the manufacturing cost is high, and it is very easy to cause voids, breakage, misalignment, etc. during the manufacturing process, resulting in TSV failure. For a silicon chip manufactured with a 65nm CMOS process technology, 46%-65% of the cost is spent on TSV processing. Therefore, the number of TSVs should be as small as possible, and the on-chip routing algorithm needs to have the function of fault recovery for TSV failure.

Therefore, a 3D NoC routing algorithm is needed to solve the communication problem in the irregular 3D NoC structure while having good TSV fault tolerance and congestion relief functions.

The design of the on-chip routing algorithm is to find an optimal balance point among several major performance indicators such as throughput, delay, and power consumption. Many scholars at home and abroad have also done a lot of research on 3D NoC routers and routing algorithms. These studies mainly focus on the following points:

1. A layered router for large-scale 3D NoC chips, which is composed of two completely separated modules, one is a 5*5 on-chip router for intra-layer communication, and the other is a 4*4 on-chip router It is used for inter-layer communication to obtain better throughput and delay in large-scale 3D NoC structures, and this method can be better applied to heterogeneous 3D NoC structures, but not suitable for small-scale 3D NoC structures. It cannot cope with the failure of some TSVs, nor does it have the function of alleviating congestion.

2. Use an elevator-priority routing algorithm to solve the communication problem in the heterogeneous 3D NoC structure with reduced TSV. This algorithm realizes inter-layer communication by assigning each network node an elevator node with upward and downward TSVs, But it does not consider the fault-tolerant processing of failure of some TSVs.

3. By adding an input port to the on-chip router to handle TSV faults and input ports, and have a congestion-aware function, but this method is not suitable for heterogeneous 3D NoC.

4. The forward-looking routing algorithm advances the routing calculation of the current node to the previous router, so that the routing calculation and the cross-switch selection are performed in parallel, thereby improving the throughput of the router. However, this improved method is not suitable for heterogeneous 3D NoC.

Contents of the invention

The present invention is to avoid the deficiencies in the above-mentioned prior art, and provides a method for establishing a channel table according to the TSV connection status of each layer in 3D NoC and its application, so as to solve the problems of data communication and TSV in irregular 3D NoC structures. Fault tolerance and packet congestion issues for vertical channels. The heterogeneous 3D NoC topology applicable to the present invention is: each layer conforms to the standard 2DMesh structure, but the structure of the layer is not necessarily the same, and each layer has several unevenly distributed TSVs connected to the previous layer or the next layer . The object of the present invention is to achieve effective data transmission in the above-mentioned heterogeneous 3D NoC structure of any scale, and it has fault-tolerant processing for failed TSVs and vertical The function of transmission channel congestion mitigation.

The present invention adopts following technical scheme for solving technical problems:

The present invention is characterized in that the method for establishing the channel table according to the TSV connection status of each layer in the 3D NoC is carried out according to the following process:

Step a: Determine the upper channel node and the lower channel node in each layer of the 3D NoC, the upper channel node refers to the node connected to the TSV above it, and the lower channel node refers to the node connected to the TSV below it ;Define all nodes in each layer of the 3D NoC except the upper channel node and the lower channel node as common nodes;

Step b: Establish a channel table for the router on each node in the 3D NoC, and use the channel table to record the upper channel node or node through which the data packet on the corresponding node needs to pass through for data transmission to the upper or lower layer. The lower channel node; and record the upper channel node and the lower channel node closest to each common node;

Step c: establish the shortest ring path through the shortest path algorithm for all upper channel nodes on each layer, and record the address of the next upper channel node in the shortest ring path in the channel table of each upper channel node; for All down channel nodes on each layer establish the shortest ring path through the shortest path algorithm, and the channel table of each down channel node records the address of the next down channel node in the shortest ring path.

The characteristics of the heterogeneous 3D NoC TSV fault-tolerant routing algorithm based on the upper and lower priority strategy of the present invention are as follows:

Step 1: For a data packet A received by the router on node A, first resolve the address of the destination node of the data packet, if the address of the destination node is the address of node A, then send the data packet A to the node A IP core, complete data transmission; otherwise, go to step 2;

Step 2: If the address of the destination node is in the current layer, use the 2D NoC round-robin routing algorithm to transmit the data packet A to the next node through the destination port to complete the data transmission of node A; if the address of the destination node is in the upper layer, then Go to step 3; if the address of the destination node is in the lower layer, go to step 5;

Step 3: If node A is an up channel node and successfully transmits data packet A through the up channel of node A, then complete the data transmission of node A; if the transmission of data packet A cannot be successfully completed through the up channel of node A, then enter the step 4; If node A is an ordinary node, go to step 4;

Step 4: Use the channel table of node A to obtain the address of node B on the upper channel available to node A, use the address of node B on the upper channel as the temporary destination address of data packet A, and route data packet A from the designated port through the 2D NoC round-robin routing algorithm Issued to complete the data transmission of node A;

Step 5: If node A is a down channel node, and the data packet A is successfully transmitted through the down channel of node A, the data transmission of node A is completed; if the transmission of data packet A cannot be successfully completed through the down channel of node A, then enter the step 6; If node A is an ordinary node, go to step 6;

Step 6: Use the channel table of node A to obtain the address of node B in the down channel available to node A, use the address of node B in the down channel as the temporary destination address of data packet A, and use the 2D NoC round-robin routing algorithm to route data packet A from the designated port Issued to complete the data transmission of node A.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. Since the present invention adopts the channel table in the 3D NoC router, for the data packet located on the common node and the destination address is located at the upper layer or the lower layer, the address of the upper channel node or the lower channel node in the channel table of the common node is used as the data The temporary destination address of the packet, transmit the data packet to the upper channel node or the lower channel node, and transmit the data packet to the upper or lower layer through the node, so as to realize effective data transmission in heterogeneous 3D NoC of any scale.

2. The present invention establishes the shortest circular path through the shortest path algorithm by all the upper channel nodes and lower channel nodes on each layer respectively in the channel table, and records in the channel tables of each upper channel node and lower channel node respectively where The address of the next channel node in the shortest ring path, so in the case of one or some TSV damage or congestion in the vertical channel, the packet can be transmitted to the next upper channel node or lower channel node for interlayer data Transmission, to achieve the function of fault-tolerant processing of failed TSVs and congestion relief of vertical transmission channels without adding redundant TSVs.

3. Compared with common 3D NoC routers, when the present invention realizes the above functions, it only needs to increase the memory for storing the channel table, and each channel table has only two data, so the increased area overhead can be ignored.

4. Compared with the common 3D NoC routing algorithm, the present invention does not add too many choices and judgments when realizing the above functions, and also has a congestion relief function for vertical channels, so the routing throughput rate will not decrease.

Description of drawings

Fig. 1 is the program flow chart of the heterogeneous 3D NoC TSV fault-tolerant routing algorithm based on the upper and lower priority strategy of the present invention

detailed description

In this embodiment, the method of establishing the channel table according to the TSV connection status of each layer in the 3D NoC is carried out as follows:

Step a: The topology applicable to this embodiment is a heterogeneous 3D NoC architecture, and not every node is connected to a TSV, so first determine the upper channel node and the lower channel node in each layer of the 3D NoC, the The upper channel node refers to the node connected to the TSV above it, and the lower channel node refers to the node connected to the TSV below it; define all the nodes in each layer of 3DNoC except the upper channel node and the lower channel node The node is a common node; a node may be only an upper channel node, a lower channel node or a normal node, or it may be both an upper channel node and a lower channel node;

Step b: The upper channel node can transmit data to the upper layer through the TSV connected above itself, and the lower channel node can transmit data to the lower layer through the TSV connected below itself, while ordinary nodes themselves cannot communicate between layers. The data packet can reach the upper or lower layer, and a channel table is established for the router on each node in the 3D NoC, and the channel table records the upper channel node that the data packet on the corresponding node needs to pass through to transmit data to the upper layer or the lower layer. or down-channel nodes; and record the up-channel nodes and down-channel nodes closest to each ordinary node; Teleport to the upper or lower layer.

Step c: When using an up-channel node or down-channel node for data transmission, the following three situations may cause data packet transmission failure: First, because the TSV manufacturing technology is not mature enough, it is caused during the chip manufacturing process TSV failures caused by TSV voids, fractures, misalignment, etc.; second, TSV failures caused by circuit aging caused by long-term use; congestion.

In order to avoid the occurrence of data packet loss or even the failure of the entire circuit board when the above situation occurs, the present invention establishes the shortest ring path through the shortest path algorithm for all upper channel nodes on each layer, and in the channel table of each upper channel node Record the address of the next upper channel node in the shortest ring path; establish the shortest ring path through the shortest path algorithm for all lower channel nodes on each layer, and record the address in the channel table of each lower channel node The address of the next down channel node in the shortest ring path. If the above three situations occur in a channel node, the channel table of the channel node can be searched, and the address of the upper channel node or the lower channel node in the channel table is used as the temporary destination address of the data packet, and the data packet is sent to the The node represented by the temporary destination address then communicates between layers. The present invention adopts the shortest circular path to connect the upper channel node and the lower channel node of each layer, which can effectively avoid the failure of the entire circuit board caused by the failure of the two adjacent channel nodes in the same layer to send data. invalidated. Therefore, under the premise of not adding redundant TSVs, the fault tolerance to TSVs can be realized through routing algorithms, and the vertical channel congestion relief function can be provided.

In this embodiment, the heterogeneous 3D NoCTSV fault-tolerant routing algorithm based on the upper and lower priority strategy utilizes the channel table and proceeds as follows:

Step 1: For a data packet A received by the router on node A, first resolve the address of the destination node of the data packet, if the address of the destination node is the address of node A, then send the data packet A to the node A IP core, complete data transmission; otherwise, go to step 2.

Step 2: If the address of the destination node is in the current layer, use the 2D NoC round-robin routing algorithm to transmit the data packet A to the next node through the destination port to complete the data transmission of node A; if the address of the destination node is in the upper layer, then Go to step 3; if the address of the destination node is in the lower layer, go to step 5.

Step 3: If node A is an up channel node and successfully transmits data packet A through the up channel of node A, then complete the data transmission of node A; if the transmission of data packet A cannot be successfully completed through the up channel of node A, then enter the step 4. The failure to successfully complete the transmission of data packet A is due to TSV failure caused by the failure of the manufacturing process of TSV itself or the aging of the circuit, or the temporary failure of data packet A to be sent due to congestion; if node A is an ordinary node, then Go to step 4.

Step 4: Use the channel table of node A to obtain the address of node B on the upper channel available to node A, use the address of node B on the upper channel as the temporary destination address of data packet A, and route data packet A from the designated port through the 2D NoC round-robin routing algorithm Issued to complete the data transmission of node A. In this embodiment, the method of changing a channel node to transmit data packet A will be able to effectively avoid the failure of the transmission of data packet A caused by the failure of the TSV connected to channel node A; When the direction channel is congested, the data packet is transferred to the channel node B for transmission, thereby alleviating the congestion of node A's vertical channel.

Step 5: If node A is a down channel node, and the data packet A is successfully transmitted through the down channel of node A, the data transmission of node A is completed; if the transmission of data packet A cannot be successfully completed through the down channel of node A, then enter the step 6; If node A is a common node, go to step 6.

Step 6: Use the channel table of node A to obtain the address of node B in the down channel available to node A, use the address of node B in the down channel as the temporary destination address of data packet A, and use the 2D NoC round-robin routing algorithm to route data packet A from the designated port Issued to complete the data transmission of node A.

The 2D NoC round-robin routing algorithm is based on "Design and Simulation of High Performance On-Chip Router Based on Random Routing" (Yue Feng, Li Runfeng, Chen Tian, Liu Jun, Chen Peng, Wang Wei. Design and Simulation of High Performance On-Chip Router Based on Random Routing, Electronics A high-performance routing algorithm proposed in the Journal of Measurement and Instrumentation [J], 2013,27(7):669-675). The algorithm is carried out as follows:

For a data packet A received by node A, first analyze the address of the destination node of the data packet, if the address of the destination node is the address of node A, then transfer the data packet A to the IP core of node A to complete the data transmission ; If only the X-axis address or the Y-axis address is the same, then transmit on the Y-axis or the X-axis through the corresponding port, and the algorithm ends; if the X-axis and Y-axis addresses are not the same, it means that there are two Transmission channels in two directions are available. If the direction identification bit in node A is "0", it will be transmitted in the X-axis direction, if it is "1", it will be transmitted in the Y-axis direction; after the transmission is completed, the identification bit will be reversed.

In the present invention, the 2D NoC round-robin routing algorithm is used for intra-layer data packet transmission, which can effectively balance the data traffic in the X-direction and Y-direction within the layer, thereby having better throughput and delay.

Claims (1)

1. A method for setting up a channel table according to each layer of TSV connection status in the 3D NoC, characterized in that it is carried out as follows: Step a: Determine the upper channel node and the lower channel node in each layer of the 3D NoC, the upper channel node refers to the node connected to the TSV above it, and the lower channel node refers to the node connected to the TSV below it ;Define all nodes in each layer of the 3D NoC except the upper channel node and the lower channel node as common nodes; Step b: Establish a channel table for the router on each node in the 3D NoC, and use the channel table to record the upper channel node or node through which the data packet on the corresponding node needs to pass through for data transmission to the upper or lower layer. The lower channel node; and record the upper channel node and the lower channel node closest to each common node; Step c: establish the shortest ring path through the shortest path algorithm for all upper channel nodes on each layer, and record the address of the next upper channel node in the shortest ring path in the channel table of each upper channel node; for All down channel nodes on each layer establish the shortest ring path through the shortest path algorithm, and the channel table of each down channel node records the address of the next down channel node in the shortest ring path.