3,422 research outputs found
Modeling and visualizing networked multi-core embedded software energy consumption
In this report we present a network-level multi-core energy model and a
software development process workflow that allows software developers to
estimate the energy consumption of multi-core embedded programs. This work
focuses on a high performance, cache-less and timing predictable embedded
processor architecture, XS1. Prior modelling work is improved to increase
accuracy, then extended to be parametric with respect to voltage and frequency
scaling (VFS) and then integrated into a larger scale model of a network of
interconnected cores. The modelling is supported by enhancements to an open
source instruction set simulator to provide the first network timing aware
simulations of the target architecture. Simulation based modelling techniques
are combined with methods of results presentation to demonstrate how such work
can be integrated into a software developer's workflow, enabling the developer
to make informed, energy aware coding decisions. A set of single-,
multi-threaded and multi-core benchmarks are used to exercise and evaluate the
models and provide use case examples for how results can be presented and
interpreted. The models all yield accuracy within an average +/-5 % error
margin
Author retrospective for the dual data cache
In this paper we present a retrospective on our paper published in ICS 1995, which to best of our knowledge was the first paper that introduced the concept of a cache memory with multiple subcaches, each tuned for a different type of locality. In this retrospective, we summarize the main ideas of the original paper and outline some of the later work that exploited similar ideas and could have been influenced by our original paper, including two actual industrial microprocessors.Peer ReviewedPostprint (author’s final draft
Overview of Swallow --- A Scalable 480-core System for Investigating the Performance and Energy Efficiency of Many-core Applications and Operating Systems
We present Swallow, a scalable many-core architecture, with a current
configuration of 480 x 32-bit processors.
Swallow is an open-source architecture, designed from the ground up to
deliver scalable increases in usable computational power to allow
experimentation with many-core applications and the operating systems that
support them.
Scalability is enabled by the creation of a tile-able system with a
low-latency interconnect, featuring an attractive communication-to-computation
ratio and the use of a distributed memory configuration.
We analyse the energy and computational and communication performances of
Swallow. The system provides 240GIPS with each core consuming 71--193mW,
dependent on workload. Power consumption per instruction is lower than almost
all systems of comparable scale.
We also show how the use of a distributed operating system (nOS) allows the
easy creation of scalable software to exploit Swallow's potential. Finally, we
show two use case studies: modelling neurons and the overlay of shared memory
on a distributed memory system.Comment: An open source release of the Swallow system design and code will
follow and references to these will be added at a later dat
Near-Memory Address Translation
Memory and logic integration on the same chip is becoming increasingly cost
effective, creating the opportunity to offload data-intensive functionality to
processing units placed inside memory chips. The introduction of memory-side
processing units (MPUs) into conventional systems faces virtual memory as the
first big showstopper: without efficient hardware support for address
translation MPUs have highly limited applicability. Unfortunately, conventional
translation mechanisms fall short of providing fast translations as
contemporary memories exceed the reach of TLBs, making expensive page walks
common.
In this paper, we are the first to show that the historically important
flexibility to map any virtual page to any page frame is unnecessary in today's
servers. We find that while limiting the associativity of the
virtual-to-physical mapping incurs no penalty, it can break the
translate-then-fetch serialization if combined with careful data placement in
the MPU's memory, allowing for translation and data fetch to proceed
independently and in parallel. We propose the Distributed Inverted Page Table
(DIPTA), a near-memory structure in which the smallest memory partition keeps
the translation information for its data share, ensuring that the translation
completes together with the data fetch. DIPTA completely eliminates the
performance overhead of translation, achieving speedups of up to 3.81x and
2.13x over conventional translation using 4KB and 1GB pages respectively.Comment: 15 pages, 9 figure
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