CN109587050A - The fault-tolerant source route algorithm of network-on-chip based on prefix - Google Patents
The fault-tolerant source route algorithm of network-on-chip based on prefix Download PDFInfo
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- CN109587050A CN109587050A CN201710902012.7A CN201710902012A CN109587050A CN 109587050 A CN109587050 A CN 109587050A CN 201710902012 A CN201710902012 A CN 201710902012A CN 109587050 A CN109587050 A CN 109587050A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/12—Shortest path evaluation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/12—Shortest path evaluation
- H04L45/121—Shortest path evaluation by minimising delays
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/24—Multipath
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/26—Route discovery packet
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L45/00—Routing or path finding of packets in data switching networks
- H04L45/70—Routing based on monitoring results
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Abstract
With the raising of circuit integration scale, for network-on-a-chip under the trend that chip area increases and characteristic size reduces, the failure cover probability being likely to occur on chip is also very important.In the service quality that network-on-chip provides, reliability is important on one side.Under the conditions of deep-submicron and nanometer technology, the fault-tolerant communications mechanism of network-on-chip has been an indispensable importance.To overcome network-on-chip link permanent error bring routing issue, a kind of fault-tolerant source route algorithm PFTSR of the network-on-chip based on prefix is invented.The algorithm is suitable for two dimension mesh network-on-chip, carries out route exploration using predicted path and according to the method for feedback information adjusts path.With the fault-tolerant source route algorithm of traditional network-on-chip, which greatly reduces the power consumption of system on chip, and in most cases can be reduced the time for detecting the first paths.
Description
Technical field
The present invention relates to the fault-tolerant of permanent fault link in network-on-chip reliability design more particularly to network-on-chip to set
Meter.
Background technique
As processor nucleus number is more and more, the data traffic between SoC each unit is increased rapidly, shared based on bus
SoC can no longer meet the communication requirement of chip chamber.At this point, network-on-chip must be used.And network-on-chip is using simultaneously
The concept of row distributed computer and traditional computer network introduces switching node between different processor cores, that is,
Router, and no longer it is bus structures.The advantage of doing so is that avoiding the communication contention aware problem of shared bus, chip is improved
Communication efficiency and the traffic.But increasing with the increase of node size and integrated level, the probability of node failure is also corresponding
Increase.In addition, chip gets over the variation of radiation and temperature as CMOS technology develops to deep-submicron, even nanometer stage
Come more sensitive, mistake also becomes increasingly difficult to predict and avoid.Under current process background, people are difficult from designing and manufacturing
Angle eliminates these mistakes, so to network-on-chip (Network-on-Chip, NoC) Fault-tolerant Routing Algorithm and various re-transmission machines
The research of system seems essential.Mistake on NoC is divided into two kinds of transient errors of transient error and permanent error and refers to signal
Bit reversal caused by crosstalk in transmission, it has Unpredictability and nonrepeatability, therefore retransmission mechanism is generally used on NoC
To overcome transient error.Permanent error refers to the permanent damage of various hardware on NoC, including link damage, router damage
It is bad etc., it is a kind of irrecoverable error.Since router damage can be considered as a kind of special link damage, various NoC hold
The main research of wrong routing algorithm is how to overcome the problems, such as that link damages.
Currently, Fault-tolerant Routing Algorithm can be divided into two kinds of non-source router operating system algorithm and source router operating system algorithm on NoC,
In non-source router operating system algorithm, grouping routing depends on the position of destination node.Non-source router operating system algorithm, which can be divided into, to be based on
The algorithm of link-local situation and algorithm based on routing table.The shortcomings that Fault-tolerant Routing Algorithm based on link-local situation algorithm
Performance is affected by breaking quantity and distribution.In the Fault-tolerant Routing Algorithm based on routing table, each node requires to create
Build and safeguard a routing table, the estimated distance that minute book node passes through all directions to other nodes in table.Each arrival section
The grouping of point determines routing direction by routing table information.The shortcomings that this kind of algorithm, is to create and safeguard that routing table needs largely
Time and space.
Compared with non-source route algorithm, source route algorithm allows source node to detect more roads for arriving destination node as needed
Diameter convenient for discovery and solves the problems, such as.In the router operating system algorithm of source, grouping routing iinformation determined by source node, how for grouping
Determine that a transmission paths are most important work.The source route algorithm of general network is applied on NoC, proposes network-on-chip
Fault-tolerant source route SRN algorithm, in the route discovery stage of the algorithm, source node use broadcast route request grouping method
Collect the address information of each intermediate node.In order to reduce the quantity of redundancy packets, intermediate node is only receiving the road for the first time
When being grouped by request and do not found the address of oneself, grouping is broadcasted.It is grouped when destination node receives route requests, it
The grouping for having recorded complete routing iinformation can be issued source node.The major defect of this algorithm is routing discovering method with blind
Mesh will cause a large amount of redundant data packets using routing packets are broadcast.For a two dimension mesh network-on-chip, source node and
Path between destination node is predictable.We can by way of prediction and according to feedback adjustment come detective path,
To reduce the quantity of route requests grouping.
Summary of the invention
The purpose of the present invention is devise a kind of piece online based on prefix to meet the needs of network-on-chip high reliability
The fault-tolerant source route algorithm of network.
The technical solution adopted by the present invention to solve the technical problems is:
The fault-tolerant source route algorithm of network-on-chip based on prefix, algorithm are carried out by the way of generating manhatton distance path at random
Route exploration, and according to drawing Feedback Information prefix to obtain off position information, open circuit starting is got around if necessary to be deviateed
Path detection power consumption of the algorithm in the route discovery stage, and can in most cases be substantially reduced first road of discovery
The time delay of diameter.It has the advantages that compress routing iinformation simultaneously and source node is allowed to detect more multipath as needed.
The algorithm requires each node to save local link information, and the link state in each direction is by a binary system
Position indicates that 0 indicates that link is normal, and 1 indicates link damage.Source node sends a route requests grouping at regular intervals.It should
Route requests grouping is not propagated using broadcast mode, specifies a possible path in advance by source node.In initial rank
Section, source node can generate a manhatton distance path to destination node at random and be encapsulated in route requests grouping, if should
Path successfully arrives at destination node without the link of damage, then destination node sends an ACK feedback packet and allows its former road
It returns.When source node receives an ACK feedback packet, then show route discovery success.If path packet along route requests grouping
Containing open circuit, then the node before open circuit can send NACK feedback packet to source node.Source node is according to drawing Feedback Information path
Prefix, to obtain off position information, and by one prefix table of local resource node maintenance.The size of prefix table is by user's root
Factually border it needs to be determined that, often extract a new prefix, resource node adds it in prefix table according to its length.Currently
Sewing table capacity and having expired or received the number of NACK feedback packet is more than a threshold value, source node can according to a prefix, around
Crossing open circuit selects an intermediate node as " pseudo- source ", by the path of pseudo- source detection to destination node.Assuming that source node A passes through road
Diameter α selects intermediate node C as pseudo- source, and C can start to detect the manhatton distance path from itself to target node b.If
C finds an available manhatton distance path β between C and B, then connects β and α, sends as an available path ξ
To source node.
The route exploration packet data structure are as follows: claimed in the route discovery stage by the grouping that (puppet) source node issues
For route requests grouping, intermediate node and destination node issue the referred to as feedback packet of (puppet) source node, they are referred to as routing
Detection grouping.The type of route exploration grouping, shares 6 seed types.Class1 is that grouping is requested in the primary routing that source node is sent,
Type 2 is the pseudo- source route requests grouping that pseudo- source node is sent;Type 3 is specified point of the pseudo- source that source node is sent to pseudo- source node
Group;Type 4 is the successful feeding back ACK that destination node is sent to source node;Type 5 is the failure that intermediate node is sent to source node
Feedback packet NACK;Type 6 is the success message pseudo-ACK that destination node is sent to pseudo- source node.
The each step of path representation and processing requirement path is indicated by two bits, can indicate 4 kinds of sides altogether
To being eastern (11), western (00), northern (10), southern (01) respectively.Indicate that path is to send feedback to source node for convenience to disappear in this way
Breath, feedback message sender need to only negate path step-by-step, so that it may obtain return path.
The pseudo- source node selection, when the number that NACK feedback packet has been expired or received to prefix table capacity is more than one
A threshold X, source node start deflection path detection.It can select a longest prefix to carry out " shake ", i.e., before open circuit
A step normal thereto is added to get around open circuit.Selection longest-prefix can be avoided as far as possible again because it is near destination node
Encounter the open circuit detected.If modified prefix is without open circuit, it can reach pseudo- source.
The processing that the routing node is grouped route exploration is that routing node first determines whether itself is the grouping
Destination node, be if it is transmitted to local resource node.Otherwise routing node can be according to the domain P and R that route exploration is grouped
Domain obtains next step direction, checks whether the link of this node corresponding direction disconnects, modifies route exploration if link is intact
The domain P of grouping simultaneously forwards grouping, is otherwise sent to local resource node.
Income of the invention is:
Overcome the problem of grouping of discovery phase broadcast route request causes bulk redundancy to be grouped；Path representation method is changed
Into compression routing iinformation；It can be found that the more path from source node to destination node；Independent of routing table, from without
A large amount of memory space and pretreatment time are wanted, extensive network-on-chip is suitable for.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples.
Fig. 1 is the data structure diagram of route exploration grouping.
Fig. 2 is network-on-chip path representation and processing schematic.
Fig. 3 is the treatment process schematic diagram that routing node is grouped route exploration packet.
Specific embodiment
The invention defines the concept of path prefix first: for any source node to any between any destination node
Path, if wherein intact but breaking, then being known as the prefix in the path.Define manhatton distance are as follows: if the length of λ is equal to,
λ is then known as to the manhatton distance path between A and B.
The algorithm requires each node to save local link information, and the link state in each direction is by bit table
Show, 0 indicates that link is normal, and 1 indicates link damage.Source node sends a route requests grouping at regular intervals.The routing
Request grouping is not propagated using broadcast mode, specifies a possible path in advance by source node.In the initial stage, source
Node can generate a manhatton distance path to destination node at random and be encapsulated in route requests grouping, if the path is not
Link by damage and successfully arrive at destination node, then destination node sends an ACK feedback packet and allows its backtracking.
When source node receives an ACK feedback packet, then show route discovery success.If path along route requests grouping includes disconnected
Road, then the node before open circuit can send NACK feedback packet to source node.Before source node is according to drawing Feedback Information path
Sew, to obtain off position information, and by one prefix table of local resource node maintenance.The size of prefix table is by user according to reality
Border it needs to be determined that, often extract a new prefix, resource node adds it in prefix table according to its length.Work as prefix table
The number that NACK feedback packet has been expired or received to capacity is more than a threshold value, and source node can be according to a prefix, around disconnected
Road selects an intermediate node as " pseudo- source ", by the path of pseudo- source detection to destination node.Assuming that source node A passage path α
Select intermediate node C as pseudo- source, C can start to detect the manhatton distance path from itself to target node b.If C is looked for
To an available manhatton distance path β between C and B, then β and α is connected, are sent to as an available path ξ
Source node.
In the invention, route requests grouping is known as by the grouping that (puppet) source node issues in the route discovery stage, it is intermediate
Node and destination node issue the referred to as feedback packet of (puppet) source node, they are referred to as route exploration grouping (RD).Fig. 1 gives
Go out the data structure of route exploration grouping, the meaning in each domain is as follows:
D and S: being the ID of destination node and source node respectively.
RSD: the ID of true source node/destination node, it is significant when T is equal to 1,2,5, it is stored when T is equal to 2
Real goal node ID stores real source node ID when T is equal to 1 or 5.
P: counter indicates routing node to obtain in next step.It can will be counted before routing node forwarding route requests grouping
Device subtracts 1, counter can be added 1 before forwarding feedback packet.
L: path length, the minimum 2L-bit store path information of R.
T: the type of route exploration grouping shares 6 seed types.Class1 is the primary routing request point that source node is sent
Group, type 2 are the pseudo- source route requests grouping that pseudo- source node is sent;Type 3 refers to for the pseudo- source that source node is sent to pseudo- source node
Fixed grouping;Type 4 is the successful feeding back ACK that destination node is sent to source node;Type 5 is that intermediate node is sent to source node
Failure feedback packet NACK;Type 6 is the success message pseudo-ACK that destination node is sent to pseudo- source node.
Shown in Fig. 2 is the method for path representation and processing.If source node 0 will generate one to destination node 24
Manhatton distance path is then in length then node 0 can first calculate the distance of east-west direction and North and South direction between two nodes
4 steps are chosen in 8 path at random to be set to eastern (11), remaining 4 step is set to southern (01).Such as (1111110101010111)2 Just
It is a possible path.When node 3 receives the grouping of the route requests comprising this paths, it judges out the side of next step
To southward, for open circuit.So node 3 can overturn path, become (0000001010101000)2, and reset route exploration point
The domain P and the domain T of group send NACK feedback packet to source node.When source node receives the NACK feedback point that node 3 is sent
Path contained by it can be negated again, obtain (1111110101010111) by group2, then extract prefix.Due to node 0 and node 3
Between manhatton distance be 3, so the 4th step in the path be open circuit, prefix be (11111101)2If it is not in prefix table
In, it can be added to prefix table according to length by source node.
Selection for pseudo- source node, in some cases, between source node and destination node and there is no available graceful
Hatton is apart from path.If source node only detects manhatton distance path, the upper only several open circuits of NoC will result in road
Failed by discovery.Simultaneously because the randomness of set calculating method, source node cannot be guaranteed to find a presence in finite time
Available manhatton distance path.In order to solve both of these problems, source node must actively modify when necessary path with
Open circuit is got around, guarantees to overcome an open circuit at least.Therefore, when time of NACK feedback packet has been expired or received to prefix table capacity
More than one threshold X of number, source node start deflection path detection.It can select a longest prefix to carry out " shake ", that is, exist
A step normal thereto is added to get around open circuit before open circuit.Selection longest-prefix can be use up because it is near destination node
Amount avoids encountering the open circuit detected again.If modified prefix is without open circuit, it can reach pseudo- source, and this prefix is known as
Healthy prefix.Once being chosen as pseudo- source node, corresponding node begins to detect the manhatton distance of other nodes.Source node
It is lasting to select pseudo- source node, until receiving ACK feedback message or alreading exceed the estimated anti-of the last one pseudo- source node
Present the time.
Shown in Fig. 3 is flow chart of each node to route exploration packet transaction, and whether routing node first determines whether itself
For the destination node of the grouping, it is if it is transmitted to local resource node.Otherwise routing node can be grouped according to route exploration
The domain P and the domain R obtain next step direction, check whether the link of this node corresponding direction disconnects, modified if link is intact
The domain P of route exploration grouping simultaneously forwards grouping, is otherwise sent to local resource node.Often receive route exploration point
It is handled as follows in group, resource node:
If (RD.D=tileID)
If (RD.T=1)
ACK is sent to RD.S;
Else if (RD.T=2)
Pseudo-ACK is sent to RD.S
Else if (RD.T=3)
Start the detection one manhatton distance path for arriving RD. RSD
Else if (RD.T=4)
One path to destination node has been found, and detection is stopped, and algorithm successfully terminates
Else if (RD.T=5)
The prefix in the corresponding path of the message is extracted, prefix table is handled
Else if (RD.T=6)
The corresponding path of the message is linked with corresponding healthy prefix, a complete path is formed, sends ACK to RD
RSD
else
If (RD.T=1)
It sends NACK message and gives RD. S.
Claims (6)
1. the fault-tolerant source route algorithm of network-on-chip based on prefix carries out road by the way of generating manhatton distance path at random
By detecting, and according to drawing Feedback Information prefix to obtain off position information, open circuit starting is got around if necessary and deviates road
Diameter has detected algorithm in the power consumption in route discovery stage, and can in most cases be substantially reduced the first paths of discovery
Time delay, it has the advantages that compress routing iinformation simultaneously and source node is allowed to detect more multipath as needed.
2. the fault-tolerant source route algorithm of the network-on-chip according to claim 1 based on prefix, it is desirable that each node saves this
The link state of ground link information, each direction is indicated that 0 indicates that link is normal by bit, and 1 indicates link damage,
Source node sends the grouping of route requests at regular intervals, route requests grouping be not propagated using broadcast mode, and
It is that a possible path is specified by source node in advance, in the initial stage, source node can generate one to destination node at random
Manhatton distance path is encapsulated in route requests grouping, if the path successfully arrives at target section without the link of damage
Point, then destination node sends an ACK feedback packet and allows its backtracking, when source node receives an ACK feedback packet, then
Show route discovery success, if path along route requests grouping includes open circuit, the node before open circuit can be sent out to source node
Send NACK feedback packet, source node is according to the prefix in drawing Feedback Information path, to obtain off position information, and by local
Resource node safeguards a prefix table, the size of prefix table by user determine according to actual needs, often extract one it is new before
Sew, resource node adds it in prefix table according to its length, when NACK feedback point has been expired or received to prefix table capacity
The number of group is more than a threshold value, and source node can select an intermediate node as " pseudo- source " according to a prefix around breaking,
By the path of pseudo- source detection to destination node, it is assumed that source node A passage path α selects intermediate node C as pseudo- source, and C can start
Detect manhatton distance path from itself to target node b, if C find an available Manhattan between C and B away from
From path β, then β and α are connected, is sent to source node as an available path ξ.
3. the fault-tolerant source route algorithm of the network-on-chip according to claim 1 based on prefix, by detection packet data structure
Are as follows: route requests grouping, intermediate node and destination node hair are known as by the grouping that (puppet) source node issues in the route discovery stage
It is known as feedback packet to (puppet) source node, they are referred to as route exploration grouping, and the type of route exploration grouping shares 6
Seed type, Class1 are that grouping is requested in the primary routing that source node is sent, and type 2 is the pseudo- source route requests that pseudo- source node is sent
Grouping;Type 3 is the pseudo- source designated packet that source node is sent to pseudo- source node;Type 4 is that destination node is sent to source node
Success feeding back ACK;Type 5 is the failure feedback packet NACK that intermediate node is sent to source node;Type 6 is destination node hair
Give the success message pseudo-ACK of pseudo- source node.
4. the fault-tolerant source route algorithm of the network-on-chip according to claim 1 based on prefix, path representation and processing are wanted
It asks each step in path to be indicated by two bits, can indicate 4 kinds of directions altogether, be respectively eastern (11), western (00), northern (10), south
(01), indicate that path is to send feedback message to source node for convenience in this way, feedback message sender only need to be by path step-by-step
It negates, so that it may obtain return path.
5. the fault-tolerant source route algorithm of the network-on-chip according to claim 1 based on prefix, pseudo- source node selection principle
For when the number that NACK feedback packet has been expired or received to prefix table capacity is more than a threshold X, source node starting deviates road
Diameter detection, it can select a longest prefix to carry out " shake ", i.e., a step normal thereto be added before open circuit to get around
Open circuit, selecting longest-prefix is that can avoid encountering the open circuit detected again as far as possible, if repairing because it is near destination node
For prefix after changing without open circuit, it can reach pseudo- source.
6. the fault-tolerant source route algorithm of the network-on-chip according to claim 1 based on prefix, the processing of route exploration grouping
For routing node first determine whether itself whether be the grouping destination node, be if it is transmitted to local resource node, otherwise
Routing node can obtain next step direction according to the domain P and the domain R that route exploration is grouped, and check that the link of this node corresponding direction is
No disconnection modifies the domain P of route exploration grouping if link is intact and forwards grouping, is otherwise sent to local resource node.
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