- Email: [email protected]
Dynamically reconfigurable multi-transputer systems with serial bus control
Microprocessing and Microprogramming 37 (1993) 149-152 North-Holland
Dynamically with serial
reconfigurable bus control
149
multi-transputer
systems
M.S. Tudruj Institute of Computer Science, Polish Academy of Sciences 01-237 Warsaw, ul. Ordona 21, Poland New architectural solutions for dynamically reconfigurable multitransputer systems are proposed in the paper. They are based on transmissions of configuration requests from worker to control transputers through the serial bus which connects selected links of these transputers.
i.
INTRODUCTION
Reconfigurable architectures attract currently much attention of multitransputer system designers. Reconfigurable systems can be easily designed for first generation transputers with the use of integrated transputer compatible crossbar switches such as the INMOS C004 switch [I]. However, mostly static reconfigurability is currently applied in multi-transputer systems, where link connections are fixed during program execution. In dynamically reconfigurable systems link connections can be reorganized during user program execution on requests sent from worker transputers to control transputers which supervise crossbar switches. The method of conveying configuration requests and other control information is an important feature in these systems since it strongly influences the efficiency of configuring actions. Dynamically reconfigurable transputer systems proposed up to now, have been based on two reconfiguration control methods: i) event driven reconfiguration control [4-6], where configuration requests, transmitted from worker transputers, activate event inputs of control transputers which configure crossbar switches, ii) parallel bus driven reconfiguration control [2,3,6], where the configuration requests and control
information are sent to control transputers by means of byte-wide control buses. In both methods configuration requests are sent outside transputer links using additional control paths and interfaces attached to involved transputers. Although, with these methods the configuration efficiency is high, it is obtained by the use of fairly complicated additional hardware interfaces, which include logical manipulations performed on transputer external memory buses. In this paper a new method for conveying both configuration requests and additional control information in dynamically reconfigurable transputer systems is proposed which involves much simpler transputer control interfaces. It is based on a serial control bus which connects selected links of worker transputers with a dedicated link of the control transputer which supervises the crossbar switch. Such transputer compatible common bus has been recently proposed [7] on the basis of the TRANSBUS controller designed and implemented at IRESTE in Nantes in France.
2.
THE
SINGLE-CLUSTER
SYSTEM
The general scheme of a simple dynamically reconfigurable transputer system based on the serial bus control is shown in Fig. i.
M.S. Tudruj
150
i conf
¢
Crossbar
Switch
Serial
Bus Host
(data,
acknowledge)
Token
Figure
i. The structure
of the s i n g l e - c l u s t e r
The system is implemented on the basis of a crossbar switch, which supports c o m m u t a t e d link connections for a single cluster of transputers. IMS T800 series t r a n s p u t e r s are used as w o r k e r t r a n s p u t e r s (WT). The IMS T222 transputer is the control t r a n s p u t e r (CT). It controls crossbar switch connection settings and implements the synchronization of configuration requests coming from different w o r k e r transputers. Three links of each w o r k e r t r a n s p u t e r are connected to the crossbar switch. The fourth link c o m m u n i c a t e s through the TRANSBUS controller (TB) with the control bus connected to a single link of the control transputer. i0 worker t r a n s p u t e r s can be interconnected using a crossbar switch of the IMS C004 type. One link of the control t r a n s p u t e r is used for the c o m m u n i c a t i o n with the host personal computer. The bus o r g a n i z e d by the TRANSBUS controller is very simple. It is composed of the data line which transmits information coming from links of c o o p e r a t i n g t r a n s p u t e r s and the a c k n o w l e d g e line which acknow-
system.
ledges each byte of i n f o r m a t i o n over the data line.
sent
The TRANSBUS controllers used as the interface b e t w e e n the control bus and all c o o p e r a t i n g t r a n s p u t e r s provide the t o k e n - b a s e d access synchronization to the bus. Input and output token lines are c o n n e c t e d to each controller to transmit the token which grants access of one t r a n s p u t e r to the bus. The protocol used for t r a n s m i s s i o n s of data over the bus is transputer compatible. Each transmission consists of three elements: the recipient address byte, the m e s s a g e length byte and the message. To e s t a b l i s h a connection in the crossbar switch a configuration request m e s s a g e is sent by a worker t r a n s p u t e r through the control bus to the control transputer. This request is r e g i s t e r e d in the m e m o r y of the control transputer. The request is next selected for servicing by polling. Then a request synchronization process is a c t i v a t e d in the control t r a n s p u t e r to implement the requested c o n n e c t i o n according to the synchronous communication model of
Dynamically reconfigurable multi-transputer systems
151
ca.f G l o b a l lMSI C 0 " 4
I
I
'"1 '" !1""'
LOCal:
j
IMS C004
.
.
(0)
i ! I
.
Serial 8 U l
S e t i a l Sun .
Token
I
L ©'~"f
°
I Ill
°
To Holt
T0ksn
~at Transp. To
lrrmnmp,
I
,,,
Figure 2. The structure of the multi-cluster the OCCAM language. When both configuration requests meet in the control transputer, the required link connection is established in the crossbar switch. Then, transputers requesting the connnection are acknowledged by means of a transmission from the control transputer over the serial control bus and the communication takes place. Sending configuration requests and acknowledges is synchronized by the token circulating between TRANSBUS controllers. The acknowledges are sent by the control transputer as a broadcast transmission containing the acknowledges for all recently established connections. In case of a communication through an already existing link connection both transputers send configuration requests to the control transputer which acknowledges both communicating processes without any configuring actions, after the synchronization of the requests. Collecting and processing the configuration requests overlap in time in the control transputer since collecting the requests is performed autonomously by transputer link interfaces. Accesses to links in worker and control transputers are controlled by multiplexer operating system
system.
processes which reserve the link usage up to the relinquishments received from respective communicating processes when the transmission is over.
3. T H E M U L T I - C L U S T E R
SYSTEM
When using the IMS C004 switches, the simple configuration shown above can be extended in two ways: i) by building a more powerful multistage crossbar switch based on the IMS C004 switches, ii) by building a system based on distributed configuration control based on several autonomous IMS C004 switches. In case i) the configuration efficiency is decreased because there is more traffic put on the control bus and transputer. In case ii) the overall configuring efficiency is increased since several crossbar switches can be controlled in parallel. The structure of a system for second case is shown in Fig. 2.
the
In this structure there are 3 clusters of i0 worker transputers, each cluster interconnected locally by a
152
M.S. Tudruj
local crossbar switch using 2 links of each worker transputer. The third link of each worker transputer is connected to the global crossbar switch which implements intercluster link connections. This switch is controlled by the global control transputer (CTG). There are three local serial control buses, one for each processor cluster. One link of the global control transputer is connected to each local control bus through a TRANSBUS controller. Intercluster link connections are established on global configuration requests sent by worker transputers to the global control transputer via the corresponding control buses. The global control transputer, after the synchronization of respective global connection requests, sets connections in the global crossbar switch and acknowledges the requesting transputers through appropriate control buses.
4. C O N C L U S I O N S
The general architecture and operation principles of the dynamically reconfigurable multi-transputer systems with the reconfiguration control based on serial bus connecting transputer links has been presented in the paper. The control serial bus has been based on the TRANSBUS controller designed at IRESTE University of Nantes. It provides the token synchronized access of transputers to the bus and the broadcast transmission facilities. Sending the connection requests to control transputers through the serial control bus suits well the configuring speed characteristics of the commercially available IMS C004 crossbar switches which are controlled by configuring messages sent in a serial way. Collecting configuration requests and setting link connections in the proposed system are performed in parallel which permits employing almost full configuring efficiency of the crossbar switch.
The proposed systems can be implemented in a simple way with an IBM PC host on the basis of the modified IMS B008-1ike 10-transputer boards which cooperate with specially built simple boards containing bus controllers and additional hardware.
REFERENCES
I. INMOS Ltd., Transputer Reference Manual, Prentice Hall, 1988. 2. Muntean T., SUPERNODE, Architecture Parallele, Dynamiquement Reconfigurable de Transputers, ll-mes Journees sur l'Informatique, Nancy, Jan. 1989. 3. Jones, P., Murta, A., The Implementation of a Run-Time LinkSwitching Environment for MultiTransputer Machines, Proc. of the NATUG2 Meeting, Durham, Oct. 1989. 4. Szturmowicz, M., Tudruj, M., A Multi -layer Transputer Network for Efficient Parallel Execution of OCCAM Programs, 15th EUROMICRO Symp. Short Notes Proc., Cologne, Sept. 1989. 5. Tudruj, M., Thor, M., A Multilayer Dynamically Reconfigurable Transputer System, PARCELLA '90 Proc., Berlin, Sept. 1990. 6. Tudruj, M., Multi-layer Reconfigurable Transputer Systems with Distributed Control of Link Connections, EUROMICRO '91 Short Notes, Proc., Vienna, Sept., 1991. 7. Calvez, J.P, Pasquier, O., A transputer interconnection bus for hard real-time systems, TRANSPUTER '92 Conf., Proc., May 20-22, 1992, Besancon, France.
Dynamically with serial
reconfigurable bus control
149
multi-transputer
systems
M.S. Tudruj Institute of Computer Science, Polish Academy of Sciences 01-237 Warsaw, ul. Ordona 21, Poland New architectural solutions for dynamically reconfigurable multitransputer systems are proposed in the paper. They are based on transmissions of configuration requests from worker to control transputers through the serial bus which connects selected links of these transputers.
i.
INTRODUCTION
Reconfigurable architectures attract currently much attention of multitransputer system designers. Reconfigurable systems can be easily designed for first generation transputers with the use of integrated transputer compatible crossbar switches such as the INMOS C004 switch [I]. However, mostly static reconfigurability is currently applied in multi-transputer systems, where link connections are fixed during program execution. In dynamically reconfigurable systems link connections can be reorganized during user program execution on requests sent from worker transputers to control transputers which supervise crossbar switches. The method of conveying configuration requests and other control information is an important feature in these systems since it strongly influences the efficiency of configuring actions. Dynamically reconfigurable transputer systems proposed up to now, have been based on two reconfiguration control methods: i) event driven reconfiguration control [4-6], where configuration requests, transmitted from worker transputers, activate event inputs of control transputers which configure crossbar switches, ii) parallel bus driven reconfiguration control [2,3,6], where the configuration requests and control
information are sent to control transputers by means of byte-wide control buses. In both methods configuration requests are sent outside transputer links using additional control paths and interfaces attached to involved transputers. Although, with these methods the configuration efficiency is high, it is obtained by the use of fairly complicated additional hardware interfaces, which include logical manipulations performed on transputer external memory buses. In this paper a new method for conveying both configuration requests and additional control information in dynamically reconfigurable transputer systems is proposed which involves much simpler transputer control interfaces. It is based on a serial control bus which connects selected links of worker transputers with a dedicated link of the control transputer which supervises the crossbar switch. Such transputer compatible common bus has been recently proposed [7] on the basis of the TRANSBUS controller designed and implemented at IRESTE in Nantes in France.
2.
THE
SINGLE-CLUSTER
SYSTEM
The general scheme of a simple dynamically reconfigurable transputer system based on the serial bus control is shown in Fig. i.
M.S. Tudruj
150
i conf
¢
Crossbar
Switch
Serial
Bus Host
(data,
acknowledge)
Token
Figure
i. The structure
of the s i n g l e - c l u s t e r
The system is implemented on the basis of a crossbar switch, which supports c o m m u t a t e d link connections for a single cluster of transputers. IMS T800 series t r a n s p u t e r s are used as w o r k e r t r a n s p u t e r s (WT). The IMS T222 transputer is the control t r a n s p u t e r (CT). It controls crossbar switch connection settings and implements the synchronization of configuration requests coming from different w o r k e r transputers. Three links of each w o r k e r t r a n s p u t e r are connected to the crossbar switch. The fourth link c o m m u n i c a t e s through the TRANSBUS controller (TB) with the control bus connected to a single link of the control transputer. i0 worker t r a n s p u t e r s can be interconnected using a crossbar switch of the IMS C004 type. One link of the control t r a n s p u t e r is used for the c o m m u n i c a t i o n with the host personal computer. The bus o r g a n i z e d by the TRANSBUS controller is very simple. It is composed of the data line which transmits information coming from links of c o o p e r a t i n g t r a n s p u t e r s and the a c k n o w l e d g e line which acknow-
system.
ledges each byte of i n f o r m a t i o n over the data line.
sent
The TRANSBUS controllers used as the interface b e t w e e n the control bus and all c o o p e r a t i n g t r a n s p u t e r s provide the t o k e n - b a s e d access synchronization to the bus. Input and output token lines are c o n n e c t e d to each controller to transmit the token which grants access of one t r a n s p u t e r to the bus. The protocol used for t r a n s m i s s i o n s of data over the bus is transputer compatible. Each transmission consists of three elements: the recipient address byte, the m e s s a g e length byte and the message. To e s t a b l i s h a connection in the crossbar switch a configuration request m e s s a g e is sent by a worker t r a n s p u t e r through the control bus to the control transputer. This request is r e g i s t e r e d in the m e m o r y of the control transputer. The request is next selected for servicing by polling. Then a request synchronization process is a c t i v a t e d in the control t r a n s p u t e r to implement the requested c o n n e c t i o n according to the synchronous communication model of
Dynamically reconfigurable multi-transputer systems
151
ca.f G l o b a l lMSI C 0 " 4
I
I
'"1 '" !1""'
LOCal:
j
IMS C004
.
.
(0)
i ! I
.
Serial 8 U l
S e t i a l Sun .
Token
I
L ©'~"f
°
I Ill
°
To Holt
T0ksn
~at Transp. To
lrrmnmp,
I
,,,
Figure 2. The structure of the multi-cluster the OCCAM language. When both configuration requests meet in the control transputer, the required link connection is established in the crossbar switch. Then, transputers requesting the connnection are acknowledged by means of a transmission from the control transputer over the serial control bus and the communication takes place. Sending configuration requests and acknowledges is synchronized by the token circulating between TRANSBUS controllers. The acknowledges are sent by the control transputer as a broadcast transmission containing the acknowledges for all recently established connections. In case of a communication through an already existing link connection both transputers send configuration requests to the control transputer which acknowledges both communicating processes without any configuring actions, after the synchronization of the requests. Collecting and processing the configuration requests overlap in time in the control transputer since collecting the requests is performed autonomously by transputer link interfaces. Accesses to links in worker and control transputers are controlled by multiplexer operating system
system.
processes which reserve the link usage up to the relinquishments received from respective communicating processes when the transmission is over.
3. T H E M U L T I - C L U S T E R
SYSTEM
When using the IMS C004 switches, the simple configuration shown above can be extended in two ways: i) by building a more powerful multistage crossbar switch based on the IMS C004 switches, ii) by building a system based on distributed configuration control based on several autonomous IMS C004 switches. In case i) the configuration efficiency is decreased because there is more traffic put on the control bus and transputer. In case ii) the overall configuring efficiency is increased since several crossbar switches can be controlled in parallel. The structure of a system for second case is shown in Fig. 2.
the
In this structure there are 3 clusters of i0 worker transputers, each cluster interconnected locally by a
152
M.S. Tudruj
local crossbar switch using 2 links of each worker transputer. The third link of each worker transputer is connected to the global crossbar switch which implements intercluster link connections. This switch is controlled by the global control transputer (CTG). There are three local serial control buses, one for each processor cluster. One link of the global control transputer is connected to each local control bus through a TRANSBUS controller. Intercluster link connections are established on global configuration requests sent by worker transputers to the global control transputer via the corresponding control buses. The global control transputer, after the synchronization of respective global connection requests, sets connections in the global crossbar switch and acknowledges the requesting transputers through appropriate control buses.
4. C O N C L U S I O N S
The general architecture and operation principles of the dynamically reconfigurable multi-transputer systems with the reconfiguration control based on serial bus connecting transputer links has been presented in the paper. The control serial bus has been based on the TRANSBUS controller designed at IRESTE University of Nantes. It provides the token synchronized access of transputers to the bus and the broadcast transmission facilities. Sending the connection requests to control transputers through the serial control bus suits well the configuring speed characteristics of the commercially available IMS C004 crossbar switches which are controlled by configuring messages sent in a serial way. Collecting configuration requests and setting link connections in the proposed system are performed in parallel which permits employing almost full configuring efficiency of the crossbar switch.
The proposed systems can be implemented in a simple way with an IBM PC host on the basis of the modified IMS B008-1ike 10-transputer boards which cooperate with specially built simple boards containing bus controllers and additional hardware.
REFERENCES
I. INMOS Ltd., Transputer Reference Manual, Prentice Hall, 1988. 2. Muntean T., SUPERNODE, Architecture Parallele, Dynamiquement Reconfigurable de Transputers, ll-mes Journees sur l'Informatique, Nancy, Jan. 1989. 3. Jones, P., Murta, A., The Implementation of a Run-Time LinkSwitching Environment for MultiTransputer Machines, Proc. of the NATUG2 Meeting, Durham, Oct. 1989. 4. Szturmowicz, M., Tudruj, M., A Multi -layer Transputer Network for Efficient Parallel Execution of OCCAM Programs, 15th EUROMICRO Symp. Short Notes Proc., Cologne, Sept. 1989. 5. Tudruj, M., Thor, M., A Multilayer Dynamically Reconfigurable Transputer System, PARCELLA '90 Proc., Berlin, Sept. 1990. 6. Tudruj, M., Multi-layer Reconfigurable Transputer Systems with Distributed Control of Link Connections, EUROMICRO '91 Short Notes, Proc., Vienna, Sept., 1991. 7. Calvez, J.P, Pasquier, O., A transputer interconnection bus for hard real-time systems, TRANSPUTER '92 Conf., Proc., May 20-22, 1992, Besancon, France.