The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
Neil Audsley - One of the best experts on this subject based on the ideXlab platform.
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predictable and efficient Virtual Addressing for safety critical real time systems
Euromicro Conference on Real-Time Systems, 2001Co-Authors: M D Bennett, Neil AudsleyAbstract:Conventionally, the use of Virtual memory in safety-critical real-time systems has been avoided, one reason being the difficulties it provides to timing analysis. The difficulties arise due to the Memory Management Unit (MMU) on commercial processors being optimised to improve average performance, to the detriment of simple worst-case analysis. However within safety-critical systems, there is a move towards implementations where processes of differing integrity levels are allocated to the same processor. This requires adequate partitioning between processes of different integrity levels. One method for achieving this in the context of commercial processor is via use of the MMU and its support for Virtual memory. The focus of this paper is upon the provision of Virtual memory for processes of all integrity levels without complicating the timing analysis of safety-critical processes with hard deadlines. Also, for lower integrity processes without hard deadlines, the flexibility of the Virtual memory provided does not restrict the process functionality, The Virtual memory system proposed is generic and can be implemented on many commercial architectures e.g. PowerPC, ARM and MIPS. This paper details the PowerPC implementation.
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ECRTS - Predictable and efficient Virtual Addressing for safety-critical real-time systems
Proceedings 13th Euromicro Conference on Real-Time Systems, 2001Co-Authors: M D Bennett, Neil AudsleyAbstract:Conventionally, the use of Virtual memory in safety-critical real-time systems has been avoided, one reason being the difficulties it provides to timing analysis. The difficulties arise due to the Memory Management Unit (MMU) on commercial processors being optimised to improve average performance, to the detriment of simple worst-case analysis. However within safety-critical systems, there is a move towards implementations where processes of differing integrity levels are allocated to the same processor. This requires adequate partitioning between processes of different integrity levels. One method for achieving this in the context of commercial processor is via use of the MMU and its support for Virtual memory. The focus of this paper is upon the provision of Virtual memory for processes of all integrity levels without complicating the timing analysis of safety-critical processes with hard deadlines. Also, for lower integrity processes without hard deadlines, the flexibility of the Virtual memory provided does not restrict the process functionality, The Virtual memory system proposed is generic and can be implemented on many commercial architectures e.g. PowerPC, ARM and MIPS. This paper details the PowerPC implementation.
Koen De Bosschere - One of the best experts on this subject based on the ideXlab platform.
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Java object header elimination for reduced memory consumption in 64-bit Virtual machines
ACM Transactions on Architecture and Code Optimization, 2007Co-Authors: Kris Venstermans, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary computer systems given the huge processor/memory speed gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We completely eliminate the object header through typed Virtual Addressing (TVA) or implicit typing. TVA encodes the object type in the object's Virtual address by allocating all objects of a given type in a contiguous memory segment. This allows for removing the type information as well as the status field from the object header. Whenever type and status information is needed, masking is applied to the object's Virtual address for obtaining an offset into type and status information structures. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated object types, hence, the name selective TVA (STVA); this limits the amount of memory fragmentation. In addition to applying STVA, we also compress the type information block (TIB) pointers for all objects that do not fall under TVA. We implement the space-efficient Java object model in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against the traditionally used Java object model using a multitude of Java benchmarks. We conclude that the space-efficient Java object model reduces memory consumption by on average 15p (and up to 45p for some benchmarks). About one-half the reduction comes from TIB pointer compression; the other one-half comes from STVA. In terms of performance, the space-efficient object model generally does not affect performance; however, for some benchmarks we observe statistically significant performance speedups, up to 20p.
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space efficient 64 bit java objects through selective typed Virtual Addressing
Symposium on Code Generation and Optimization, 2006Co-Authors: Kris Venstermans, Lieven Eeckhout, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary systems given the ever increasing memory gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We propose selective typed Virtual Addressing (STVA) which uses typed Virtual Addressing (TVA) or implicit typing for reducing the header of 64-bit Java objects. The idea behind TVA is to encode the object's type in the object's Virtual address. In other words, all objects of a given type are allocated in a contiguous memory segment. As such, the type information can be removed from the object's header which reduces the number of allocated bytes per object. Whenever type information is needed for the given object, masking is applied to the object's Virtual address. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated and/or long-lived object types. This limits the amount of memory fragmentation. We implement STVA in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against a traditional VM implementation without STVA using a multitude of Java benchmarks. We conclude that STVA reduces memory consumption by on average 15.5% (and up to 39% for some benchmarks). In terms of performance, STVA generally does not affect performance, however for some benchmarks we observe statistically significant performance speedups, up to 24%.
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CGO - Space-Efficient 64-bit Java Objects through Selective Typed Virtual Addressing
International Symposium on Code Generation and Optimization (CGO'06), 1Co-Authors: Kris Venstermans, Lieven Eeckhout, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary systems given the ever increasing memory gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We propose selective typed Virtual Addressing (STVA) which uses typed Virtual Addressing (TVA) or implicit typing for reducing the header of 64-bit Java objects. The idea behind TVA is to encode the object's type in the object's Virtual address. In other words, all objects of a given type are allocated in a contiguous memory segment. As such, the type information can be removed from the object's header which reduces the number of allocated bytes per object. Whenever type information is needed for the given object, masking is applied to the object's Virtual address. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated and/or long-lived object types. This limits the amount of memory fragmentation. We implement STVA in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against a traditional VM implementation without STVA using a multitude of Java benchmarks. We conclude that STVA reduces memory consumption by on average 15.5% (and up to 39% for some benchmarks). In terms of performance, STVA generally does not affect performance, however for some benchmarks we observe statistically significant performance speedups, up to 24%.
M D Bennett - One of the best experts on this subject based on the ideXlab platform.
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predictable and efficient Virtual Addressing for safety critical real time systems
Euromicro Conference on Real-Time Systems, 2001Co-Authors: M D Bennett, Neil AudsleyAbstract:Conventionally, the use of Virtual memory in safety-critical real-time systems has been avoided, one reason being the difficulties it provides to timing analysis. The difficulties arise due to the Memory Management Unit (MMU) on commercial processors being optimised to improve average performance, to the detriment of simple worst-case analysis. However within safety-critical systems, there is a move towards implementations where processes of differing integrity levels are allocated to the same processor. This requires adequate partitioning between processes of different integrity levels. One method for achieving this in the context of commercial processor is via use of the MMU and its support for Virtual memory. The focus of this paper is upon the provision of Virtual memory for processes of all integrity levels without complicating the timing analysis of safety-critical processes with hard deadlines. Also, for lower integrity processes without hard deadlines, the flexibility of the Virtual memory provided does not restrict the process functionality, The Virtual memory system proposed is generic and can be implemented on many commercial architectures e.g. PowerPC, ARM and MIPS. This paper details the PowerPC implementation.
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ECRTS - Predictable and efficient Virtual Addressing for safety-critical real-time systems
Proceedings 13th Euromicro Conference on Real-Time Systems, 2001Co-Authors: M D Bennett, Neil AudsleyAbstract:Conventionally, the use of Virtual memory in safety-critical real-time systems has been avoided, one reason being the difficulties it provides to timing analysis. The difficulties arise due to the Memory Management Unit (MMU) on commercial processors being optimised to improve average performance, to the detriment of simple worst-case analysis. However within safety-critical systems, there is a move towards implementations where processes of differing integrity levels are allocated to the same processor. This requires adequate partitioning between processes of different integrity levels. One method for achieving this in the context of commercial processor is via use of the MMU and its support for Virtual memory. The focus of this paper is upon the provision of Virtual memory for processes of all integrity levels without complicating the timing analysis of safety-critical processes with hard deadlines. Also, for lower integrity processes without hard deadlines, the flexibility of the Virtual memory provided does not restrict the process functionality, The Virtual memory system proposed is generic and can be implemented on many commercial architectures e.g. PowerPC, ARM and MIPS. This paper details the PowerPC implementation.
Kris Venstermans - One of the best experts on this subject based on the ideXlab platform.
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Java object header elimination for reduced memory consumption in 64-bit Virtual machines
ACM Transactions on Architecture and Code Optimization, 2007Co-Authors: Kris Venstermans, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary computer systems given the huge processor/memory speed gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We completely eliminate the object header through typed Virtual Addressing (TVA) or implicit typing. TVA encodes the object type in the object's Virtual address by allocating all objects of a given type in a contiguous memory segment. This allows for removing the type information as well as the status field from the object header. Whenever type and status information is needed, masking is applied to the object's Virtual address for obtaining an offset into type and status information structures. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated object types, hence, the name selective TVA (STVA); this limits the amount of memory fragmentation. In addition to applying STVA, we also compress the type information block (TIB) pointers for all objects that do not fall under TVA. We implement the space-efficient Java object model in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against the traditionally used Java object model using a multitude of Java benchmarks. We conclude that the space-efficient Java object model reduces memory consumption by on average 15p (and up to 45p for some benchmarks). About one-half the reduction comes from TIB pointer compression; the other one-half comes from STVA. In terms of performance, the space-efficient object model generally does not affect performance; however, for some benchmarks we observe statistically significant performance speedups, up to 20p.
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space efficient 64 bit java objects through selective typed Virtual Addressing
Symposium on Code Generation and Optimization, 2006Co-Authors: Kris Venstermans, Lieven Eeckhout, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary systems given the ever increasing memory gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We propose selective typed Virtual Addressing (STVA) which uses typed Virtual Addressing (TVA) or implicit typing for reducing the header of 64-bit Java objects. The idea behind TVA is to encode the object's type in the object's Virtual address. In other words, all objects of a given type are allocated in a contiguous memory segment. As such, the type information can be removed from the object's header which reduces the number of allocated bytes per object. Whenever type information is needed for the given object, masking is applied to the object's Virtual address. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated and/or long-lived object types. This limits the amount of memory fragmentation. We implement STVA in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against a traditional VM implementation without STVA using a multitude of Java benchmarks. We conclude that STVA reduces memory consumption by on average 15.5% (and up to 39% for some benchmarks). In terms of performance, STVA generally does not affect performance, however for some benchmarks we observe statistically significant performance speedups, up to 24%.
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CGO - Space-Efficient 64-bit Java Objects through Selective Typed Virtual Addressing
International Symposium on Code Generation and Optimization (CGO'06), 1Co-Authors: Kris Venstermans, Lieven Eeckhout, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary systems given the ever increasing memory gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We propose selective typed Virtual Addressing (STVA) which uses typed Virtual Addressing (TVA) or implicit typing for reducing the header of 64-bit Java objects. The idea behind TVA is to encode the object's type in the object's Virtual address. In other words, all objects of a given type are allocated in a contiguous memory segment. As such, the type information can be removed from the object's header which reduces the number of allocated bytes per object. Whenever type information is needed for the given object, masking is applied to the object's Virtual address. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated and/or long-lived object types. This limits the amount of memory fragmentation. We implement STVA in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against a traditional VM implementation without STVA using a multitude of Java benchmarks. We conclude that STVA reduces memory consumption by on average 15.5% (and up to 39% for some benchmarks). In terms of performance, STVA generally does not affect performance, however for some benchmarks we observe statistically significant performance speedups, up to 24%.
Lieven Eeckhout - One of the best experts on this subject based on the ideXlab platform.
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space efficient 64 bit java objects through selective typed Virtual Addressing
Symposium on Code Generation and Optimization, 2006Co-Authors: Kris Venstermans, Lieven Eeckhout, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary systems given the ever increasing memory gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We propose selective typed Virtual Addressing (STVA) which uses typed Virtual Addressing (TVA) or implicit typing for reducing the header of 64-bit Java objects. The idea behind TVA is to encode the object's type in the object's Virtual address. In other words, all objects of a given type are allocated in a contiguous memory segment. As such, the type information can be removed from the object's header which reduces the number of allocated bytes per object. Whenever type information is needed for the given object, masking is applied to the object's Virtual address. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated and/or long-lived object types. This limits the amount of memory fragmentation. We implement STVA in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against a traditional VM implementation without STVA using a multitude of Java benchmarks. We conclude that STVA reduces memory consumption by on average 15.5% (and up to 39% for some benchmarks). In terms of performance, STVA generally does not affect performance, however for some benchmarks we observe statistically significant performance speedups, up to 24%.
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CGO - Space-Efficient 64-bit Java Objects through Selective Typed Virtual Addressing
International Symposium on Code Generation and Optimization (CGO'06), 1Co-Authors: Kris Venstermans, Lieven Eeckhout, Koen De BosschereAbstract:Memory performance is an important design issue for contemporary systems given the ever increasing memory gap. This paper proposes a space-efficient Java object model for reducing the memory consumption of 64-bit Java Virtual machines. We propose selective typed Virtual Addressing (STVA) which uses typed Virtual Addressing (TVA) or implicit typing for reducing the header of 64-bit Java objects. The idea behind TVA is to encode the object's type in the object's Virtual address. In other words, all objects of a given type are allocated in a contiguous memory segment. As such, the type information can be removed from the object's header which reduces the number of allocated bytes per object. Whenever type information is needed for the given object, masking is applied to the object's Virtual address. Unlike previous work on implicit typing, we apply TVA to a selected number of frequently allocated and/or long-lived object types. This limits the amount of memory fragmentation. We implement STVA in the 64-bit version of the Jikes RVM on an AIX IBM platform and compare its performance against a traditional VM implementation without STVA using a multitude of Java benchmarks. We conclude that STVA reduces memory consumption by on average 15.5% (and up to 39% for some benchmarks). In terms of performance, STVA generally does not affect performance, however for some benchmarks we observe statistically significant performance speedups, up to 24%.
