International Business Machines Corporation

David W Siegel

Ravi Kumar Arimilli

Sudhir Dhawan

James O Nicholson

Naresh Nayar

James Xenidis

Prabhakar Nandavar Kudva

Pia Naoko Sanda

James Lee Van Oosten

Daniel James Henderson

George A Lerom

An attribute of a descriptor associated with a task informs a runtime environment of which instructions a processor is to run to schedule a plurality if resources for completion of the task in accordance with a level of quality of service in a service level agreement.

Tunable error resilience computing

Apparatus and method for improving the rate of transfer of data in the context of a system memory operated in conjunction with a cache. In one form, mask bits in a mask bit register are associated to bytes of cache. The mask bits are changed in state when the corresponding byte in the cache is written. The mask bits are used in a reordered operating sequence to selectively write data from system memory into the cache after a write into cache. Data transfer performance is improved significantly in that the selective writing of data from system memory to cache can be completely eliminated when the mask bits indicate that a whole unit of the cache, typically a cache line, has been written during the data transfer into the cache.

Cache system using mask bits to recorder the sequences for transfers of

A DMA controller coupled to two separate buses controls the transfer of data between them. To effect a block data transfer, data is simultaneously read on one bus and written on the other. This allows data to be transferred between buses at the maximum transfer rate supported by the slower bus.

Computer system DMA transfer

A cache for use with input/output devices attached to an input/output bus. Requests for access to system memory by an input/output device pass through the cache. Virtual memory addresses used by the input/output devices are translated into real addresses in the system memory. Virtual memory can be partitioned, with some virtual addresses being mapped to a second memory attached to the input/output bus.

Input/output cache

A computer system can transfer data between a master subsystem and a slave subsystem on bus address lines as well as bus data lines during a high speed data transfer. Data is clocked during the high speed transfer by a high speed clock signal which is separate from a normal bus clock signal. Data is transferred at the maximum rate which can be handled by both the master subsystem and the slave subsystem.

Data transfer using bus address lines

A computer system bus includes signal lines for controlling a high speed block data transfer mode between a bus master and a bus slave. When both devices support such a transfer, a high speed bus clock separate from the normal bus clock is used to transfer data. Devices not involved in the high speed block transfer see only an extended normal data transfer. The master and slave use bus control signals to determine the speed and data width of the high speed transfer. If the slave is unable to transfer the complete block of data at the high speed clock rate, it can signal the master to repeat the transfer of individual data items as necessary.

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Austin, TX, United States of America

David W Siegel