Virtual-physical registers

A novel dynamic register renaming approach is proposed in this work. The key idea of the novel scheme is to delay the allocation of physical registers until a late stage in the pipeline, instead of doing it in the decode stage as conventional schemes do. In this way, the register pressure is reduced and the processor can exploit more instruction-level parallelism. Delaying the allocation of physical registers require some additional artifact to keep track of dependences. This is achieved by introducing the concept of virtual-physical registers, which do not require any storage location and are used to identify dependences among instructions that have not yet allocated a register to its destination operand. Two alternative allocation strategies have been investigated that differ in the stage where physical registers are allocated: issue or write-back. The experimental evaluation has confirmed the higher performance of the latter alternative. We have performed all evaluation of the novel scheme through a detailed simulation of a dynamically scheduled processor. The results show a significant improvement (e.g., 19% increase in IPC for a machine with 64 physical registers in each file) when compared with the traditional register renaming approach.Peer ReviewedPostprint (published version

A STUDY ON THE REGISTERS USED BY PHOTOGRAPHIC COMMUNITY OF MUHAMMADIYAH UNIVERSITY OF MALANG

Register is another factor in any study of language varieties. Registers are language varieties that are used by the people in particular settings and situations. In this study, the writer investigates the registers that are used by the photographic community of Muhammadiyah University of Malang and the registers that differ from lexical meaning. The investigation is done because the writer is interested in finding the registers used by the photographic community of Muhammadiyah University of Malang and the registers that differ from lexical meaning. The writer believes that some of photographic registers are different from lexical meaning. Besides, there are a few of researchers who have studied about registers, especially about photographic registers. This study is conducted to give contribution for English department, such as to enrich the knowledge of English department students about how sociolinguistic phenomena in photographic community environment, and to develop the ability of language and sociolinguistics among them. The researcher used a descriptive qualitative research design to describe and interpret the registers used by the photographic community of Muhammadiyah University of Malang and the registers that differs from lexical meaning. The subject of this study was a part of the photographic community of Muhammadiyah University of Malang. The informants taken from the photographic community were 12 persons. To collect the data, the writer used interview and observation. In the observation, the writer observed the dialogues among the photographers in Muhammadiyah University of Malang. Then, the writer conducted data triangulation in order to get the valid data. To analyze the data, the writer used several steps as follows: 1) Identifying the data of the photographic registers, 2) Analyzing the photographic registers based on their categories, 3) Comparing the photographic registers meaning with lexical meaning, 4) Arranging the data in the form of table, 5) Drawing conclusion based on the data. The result of this study shows that from 71 registers used by the photographic community, there are 49 registers that differ from lexical meaning and 18 registers are similar with their lexical meaning. Finally, the writer suggests that this study will encourage other researchers to conduct better researches, especially in Sociolinguistics subject

On the Importance of Registers for Computability

All consensus hierarchies in the literature assume that we have, in addition to copies of a given object, an unbounded number of registers. But why do we really need these registers? This paper considers what would happen if one attempts to solve consensus using various objects but without any registers. We show that under a reasonable assumption, objects like queues and stacks cannot emulate the missing registers. We also show that, perhaps surprisingly, initialization, shown to have no computational consequences when registers are readily available, is crucial in determining the synchronization power of objects when no registers are allowed. Finally, we show that without registers, the number of available objects affects the level of consensus that can be solved. Our work thus raises the question of whether consensus hierarchies which assume an unbounded number of registers truly capture synchronization power, and begins a line of research aimed at better understanding the interaction between read-write memory and the powerful synchronization operations available on modern architectures.Comment: 12 pages, 0 figure

Decoherence of quantum registers

The dynamical evolution of a quantum register of arbitrary length coupled to an environment of arbitrary coherence length is predicted within a relevant model of decoherence. The results are reported for quantum bits (qubits) coupling individually to different environments (`independent decoherence') and qubits interacting collectively with the same reservoir (`collective decoherence'). In both cases, explicit decoherence functions are derived for any number of qubits. The decay of the coherences of the register is shown to strongly depend on the input states: we show that this sensitivity is a characteristic of $both$ types of coupling (collective and independent) and not only of the collective coupling, as has been reported previously. A non-trivial behaviour ("recoherence") is found in the decay of the off-diagonal elements of the reduced density matrix in the specific situation of independent decoherence. Our results lead to the identification of decoherence-free states in the collective decoherence limit. These states belong to subspaces of the system's Hilbert space that do not get entangled with the environment, making them ideal elements for the engineering of ``noiseless'' quantum codes. We also discuss the relations between decoherence of the quantum register and computational complexity based on the new dynamical results obtained for the register density matrix.Comment: Typos corrected. Discussion and references added. 1 figure + 3 tables added. This updated version contains 13 (double column) pages + 8 figures. PRA in pres

Consensus with Max Registers

We consider the problem of implementing randomized wait-free consensus from max registers under the assumption of an oblivious adversary. We show that max registers solve m-valued consensus for arbitrary m in expected O(log^* n) steps per process, beating the Omega(log m/log log m) lower bound for ordinary registers when m is large and the best previously known O(log log n) upper bound when m is small. A simple max-register implementation based on double-collect snapshots translates this result into an O(n log n) expected step implementation of m-valued consensus from n single-writer registers, improving on the best previously-known bound of O(n log^2 n) for single-writer registers