In time series editing, we aim to modify some properties of a given time series without altering others. For example, when analyzing a hospital patient's blood pressure, we may add a sudden early drop and observe how it impacts their future, while preserving other conditions. Existing diffusion-based editors rely on rigid, predefined attribute vectors as conditions and produce all-or-nothing edits through sampling. This attribute- and sampling-based approach limits flexibility in condition format and lacks customizable control over editing strength. To overcome these limitations, we introduce Instruction-based Time Series Editing, where users specify intended edits using natural language. This allows users to express a wider range of edits in a more accessible format. We then introduce InstructTime, the first instruction-based time series editor. InstructTime takes in time series and instructions, embeds them into a shared multi-modal representation space, then decodes their embeddings to generate edited time series. By learning a structured multi-modal representation space, we can easily interpolate between embeddings to achieve varying degrees of edit. To handle local and global edits together, we propose multi-resolution encoders. In our experiments, we use synthetic and real datasets and find that InstructTime is a state-of-the-art time series editor: InstructTime achieves high-quality edits with controllable strength, can generalize to unseen instructions, and can be easily adapted to unseen conditions through few-shot learning.

Emerging heavy-load mobile apps like UHD video and AR/VR access diverse high-throughput hardware devices, e.g., video codecs and cameras. However, today's mobile emulators exhibit poor performance when emulating these devices. We pinpoint the major reason to be the discrepancy between the guest's (system-on-chip) and host's (PC or cloud server) memory architectures for these devices, which makes the shared virtual memory (SVM) architecture of mobile emulators highly inefficient. To address this, we introduce vSoC, the first virtual mobile SoC featuring aunifiedSVM framework that enables efficient and secure data sharing among virtual devices, as well as anintelligentprefetch engine that effectively eliminates the vast majority of coherence maintenance overhead. While vSoC addresses runtime performance issues, app developers face a severe debugging challenge due to the inability of traditional tools to capture complete system states. Therefore, we devise an adaptive VM (virtual machine) snapshot-based approach that dynamically selects the optimal resource loading strategy to make vSoC debug-friendly. Compared to state-of-the-art emulators, vSoC brings 1.8–9.0$\times$frame rates, 35%-62% lower motion-tophoton latency, and 6.5–14.4$\times$bug reproduction rates for heavyload apps. It is applicable to a variety of scenarios like end-user high-performance emulation and cloud/web-based rendering.

Emerging mobile apps such as UHD video and AR/VR access diverse high-throughput hardware devices, e.g., video codecs, cameras, and image processors. However, today's mobile emulators exhibit poor performance when emulating these devices. We pinpoint the major reason to be the discrepancy between the guest's and host's memory architectures for hardware devices, i.e., the mobile guest's centralized memory on a system-on-chip (SoC) versus the PC/server's separated memory modules on individual hardware. Such a discrepancy makes the shared virtual memory (SVM) architecture of mobile emulators highly inefficient.

Android system has been widely deployed in energy-constrained IoT devices for many practical applications, such as smart phone, smart home, healthcare, fitness, and beacons. However, Android users oftentimes suffer from app crashes, which directly disrupt user experience and could lead to data loss. Till now, the community have limited understanding of their prevalence, characteristics, and root causes. In this article, we make an in-depth study of the crash events regarding ten very popular apps of different genres, based on fine-grained system-level traces crowd-sourced from 93 million Android devices. We find that app crashes occur prevalently on the various hardware models studied, and better hardware does not seem to essentially relieve the problem. Most importantly, we unravel multi-fold root causes of app crashes, and pinpoint that the most crashes stem from the subtle yet crucial inconsistency between app developers’ supposed memory/process management model and Android’s actual implementations. We design practical approaches to addressing the inconsistency; after large-scale deployment, they reduce 40.4% of the app crashes with negligible system overhead. In addition, we summarize important lessons learned from this study, and have released our measurement code/data to the community.

Virtual devices based on device emulation have been widely used in lab research of mobile app testing for their efficiency and low cost. However, it remains controversial to use virtual devices for app testing in industry, given the inherent difficulties of high-fidelity emulation across diverse mobile systems and devices. Hence, mobile app companies still rely on physical device farms or services like AWS Device Farm.