Balancing Design Options with Sherpa

Application specific processors offer the potential of rapidly designed logic specifically constructed to meet the performance and area demands of the task at hand. Recently, there have been several major projects that attempt to automate the process of transforming a predetermined processor configuration into a low level description for fabrication. These projects either leave the specification of the processor to the designer, which can be a significant engineering burden, or handle it in a fully automated fashion, which completely removes the designer from the loop. In this paper we introduce a technique for guiding the design and optimization of application specific processors. The goal of the Sherpa design framework is to automate certain design tasks and provide early feedback to help the designer navigate their way through the architecture design space. Our approach is to decompose the overall problem of choosing an optimal architecture into a set of sub-problems that are, to the first order, independent. For each subproblem, we create a model that relates performance to area. From this, we build a constraint system that can be solved using integer-linear programming techniques, and arrive at an ideal parameter selection for all architectural components. Our approach only takes a few minutes to explore the design space allowing the designer or compiler to see the potential benefits of optimizations rapidly. We show that the expected performance using our model correlates strongly to detailed pipeline simulations, and present results showing design tradeoffs for several different benchmarks

Reproducible simulation of multi-threaded workloads for architecture design exploration

As multiprocessors become mainstream, techniques to ad-dress efficient simulation of multi-threaded workloads are needed. Multi-threaded simulation presents a new challenge: non-determinism across simulations for different architecture configurations. If the execution paths between two simulation runs of the same benchmark with the same input are too different, the simulation results cannot be used to compare the configurations. In this paper we focus on a simulation technique to efficiently collect simulation checkpoints for multi-threaded workloads, and to compare simulation runs addressing this non-determinism problem. We focus on user-level simulation of multi-threaded workloads for multiprocessor architectures. We present an approach, based on binary instrumentation, to collect checkpoints for simulation. Our checkpoints allow reproducible execution of the samples across different ar-chitecture configurations by controlling the sources of non-determinism during simulation. This results in stalls that would not naturally occur in execution. We propose techniques that allow us to accurately compare performance across architec-ture configurations in the presence of these stalls. I

Oleic Acid Counters Impaired Blastocyst Development Induced by Palmitic Acid During Mouse Preimplantation Development: Understanding Obesity-Related Declines in Fertility

Obesity is associated with altered fatty acid profiles, reduced fertility, and assisted reproductive technology (ART) success. The effects of palmitic acid (PA), oleic acid (OA), and their combination on mouse preimplantation development, endoplasmic reticulum (ER) stress pathway gene expression, lipid droplet formation, and mitochondrial reactive oxygen species (ROS) were characterized. Two-cell stage mouse embryos collected from superovulated and mated CD1 females were placed into culture with KSOMaa medium, or PA alone or in combination with OA for 46 h. PA significantly reduced blastocyst development in a concentration-dependent manner, which was prevented by co-treatment with OA. PA and OA levels in mouse reproductive tracts were assessed by liquid chromatography coupled to mass spectrometry (LC-MS). LC-MS indicated higher concentrations of PA in the mouse oviduct than the uterus. Transcript analysis revealed that PA alone groups had increased ER stress pathway (ATF3, CHOP, and XBP1 splicing) mRNAs, which was alleviated by OA co-treatment. OA co-treatment significantly increased lipid droplet accumulation and significantly decreased mitochondrial ROS from PA treatment alone. PA treatment for only 24 h significantly reduced its impact on blastocyst development from the 2-cell stage. Thus, PA affects ER stress pathway gene expression, lipid droplet accumulation, and mitochondrial ROS in treated preimplantation embryos. These mechanisms may serve to offset free fatty acid exposure effects on preimplantation development, but their protective ability may be overwhelmed by elevated PA

HALO: Post-Link Heap-Layout Optimisation

Today, general-purpose memory allocators dominate the landscape of dynamic memory management. While these so- lutions can provide reasonably good behaviour across a wide range of workloads, it is an unfortunate reality that their behaviour for any particular workload can be highly suboptimal. By catering primarily to average and worst-case usage patterns, these allocators deny programs the advantages of domain-specific optimisations, and thus may inadvertently place data in a manner that hinders performance, generating unnecessary cache misses and load stalls. To help alleviate these issues, we propose HALO: a post-link profile-guided optimisation tool that can improve the layout of heap data to reduce cache misses automatically. Profiling the target binary to understand how allocations made in different contexts are related, we specialise memory-management routines to allocate groups of related objects from separate pools to increase their spatial locality. Unlike other solutions of its kind, HALO employs novel grouping and identification algorithms which allow it to create tight-knit allocation groups using the entire call stack and to identify these efficiently at runtime. Evaluation of HALO on contemporary out-of-order hardware demonstrates speedups of up to 28% over jemalloc, out-performing a state-of-the-art data placement technique from the literature

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions

Catching element formation in the act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions

Patchable Instruction ROM Architecture

Increased systems level integration has meant the movement of many traditionally off chip components onto a single chip including a processor, instruction storage, data path, and local memory. The design of these systems are driven by two conflicting goals, the need for reduced area and the need for rapid development times. The two current design options for instruction storage, ROM and Flash, are each highly optimized to one of these two goals but provide little compromise between them. ROM is used for highly area optimized instruction memory to minimize area per instruction, although this comes at a price of lengthy integration time because of it's need to be correct before the chip is sent for fabrication. Flash is an alternative instruction memory that can significantly reduce the time to market by allowing embedded software to be upgraded after fabrication, which means that software test and fabrication can be overlapped. Unfortunately Flash takes over a factor of 2 times the area of the equivalent ROM based storage. In this paper we present the Patchable Instruction ROM as an architecture for instruction storage that can provide the best of both worlds -- reduced area and faster time to market. With area efficiency similar to a standard ROM and support for limited post fabrication software patching, Patchable Instruction ROM provides a new set of design points to consider when building embedded systems. For the programs we examine, we show that our hardware/software technique can achieve an area only 10% larger than ROM with only an 11% inflation in design time over a Flash based approach.Pre-2018 CSE ID: CS2001-067