Role of phase synchronisation in turbulence

The role of the phase dynamics in turbulence is investigated. As a demonstration of the importance of the phase dynamics, a simplified system is used, namely the one-dimensional Burgers equation, which is evolved numerically. The system is forced via a known external force, with two components that are added into the evolution equations of the amplitudes and the phase of the Fourier modes, separately. In this way, we are able to control the impact of the force on the dynamics of the phases. In the absence of the direct forcing in the phase equation, it is observed that the phases are not stochastic as assumed in the Random Phase Approximation (RPA) models, and in contrast, the non-linear couplings result in intermittent locking of the phases to ± π/2. The impact of the force, applied purely on the phases, is to increase the occurrence of the phase locking events in which the phases of the modes in a wide k range are now locked to ± π/2, leading to a change in the dynamics of both phases and amplitudes, with a significant localization of the real space flow structures

Aligned Scheduling: Cache-efficient Instruction Scheduling for VLIW Processors ⋆

Abstract. The performance of statically scheduled VLIW processors is highly sensitive to the instruction scheduling performed by the compiler. In this work we identify a major deficiency in existing instruction scheduling for VLIW processors. Unlike most dynamically scheduled processors, a VLIW processor with no load-use hardware interlocks will completely stall upon a cache-miss of any of the operations that are scheduled to run in parallel. Other operations in the same or subsequent instruction words must stall. However, if coupled with non-blocking caches, the VLIW processor is capable of simultaneously resolving multiple loads from the same word. Existing instruction scheduling algorithms do not optimize for this VLIW-specific problem. We propose Aligned Scheduling, a novel instruction scheduling algorithm that improves performance of VLIW processors with non-blocking caches by enabling them to better cope with unpredictable cache-memory latencies. Aligned Scheduling exploits the VLIW-specific cache-miss semantics to efficiently align cache misses on the same scheduling cycle, increasing the probability that they get serviced simultaneously. Our evaluation shows that Aligned Scheduling improves the performance of VLIW processors across a range of benchmarks from the Mediabench II and SPEC CINT2000 benchmark suites up to 20%.

Evrei v menyayushchemsya mire Materialy 3. mezhdunarodnoj konferentsii

Available from Latvian Academic Library / LAL - Latvian Academic LibrarySIGLEMemorial Foundation for Jewish Culture, New York, NY (United States); Soros Foundation - Latvia, Riga (Latvia)LVLatvi

Evrei v menyayushchemsya mire Materialy 2. mezhdunarodnoj konferentsii

Available from Latvian Academic Library / LAL - Latvian Academic LibrarySIGLEMemorial Foundation for Jewish Culture, New York, NY (United States); Soros Foundation - Latvia, Riga (Latvia)LVLatvi