Few-shot object detection (FSOD) within remote sensing imagery has achieved great advancements in recent years. However, most existing methods are facing one key challenge while handling remote sensing images: many unlabeled instances in few-shot images are treated as background, which tends to degrade the generalization of the trained model severely. This paper presents HPMF, a Hypergraph-guided Prototype Mining Framework that addresses the challenge through joint optimization from three perspectives. The first is Hierarchical Reference Mining (HRM) which constructs a class-instance dual-driven prototype space that enables mining the unlabeled instances via cross-hierarchical similarity fusion. The second is a Robust Pseudo-box Estimator (RPE) that generates high-quality pseudo bounding boxes for the HRM-mined instances via adaptive density clustering and multi-statistic aggregation. The third is a Hypergraph-Guided Decoder (HGD) that introduces hypergraphs into the transformer decoder for group semantic modeling, enhancing high-order semantic association and similarity of instance features, thereby further improving the mining performance of the HRM module. Extensive experiments under various settings show that the proposed HPMF outperforms state-of-the-art methods consistently across multiple widely adopted remote-sensing FSOD benchmarks such as DIOR, NWPU-VHR10 v2, and HRRSD.

This work presents (a) Queenie, an application-level tool that can automatically learn 10 internal properties of block-level SSDs, (b) Kelpie, the learning and analysis results of running Queenie on 21 different SSD models from 7 major SSD vendors, and (c) Newt, a set of storage performance optimization examples that use the learned properties. By bringing numerous observations and unique findings, this work exposes substantial improvement spaces for both SSD users and vendors, enlightening possibilities of unleashing more SSD performance potential and highlighting the necessity of further exploring SSD internals.

Today's cloud storage stack is extremely resource hungry, burning 10-20% of datacenter x86 cores, a major "storage tax" that cloud providers must pay. Yet, the complex cloud storage stack is not completely offload-ready to today's IO accelerators. We present LeapIO, a new cloud storage stack that leverages ARM-based co-processors to offload complex storage services. LeapIO addresses many deployment challenges, such as hardware fungibility, software portability, virtualizability, composability, and efficiency. It uses a set of OS/software techniques and new hardware properties that provide a uni- form address space across the x86 and ARM cores and ex- pose virtual NVMe storage to unmodified guest VMs, at a performance that is competitive with bare-metal servers.

Fail-slow hardware is an under-studied failure mode. We present a study of 114 reports of fail-slow hardware incidents, collected from large-scale cluster deployments in 14 institutions. We show that all hardware types such as disk, SSD, CPU, memory, and network components can exhibit performance faults. We made several important observations such as faults convert from one form to another, the cascading root causes and impacts can be long, and fail-slow faults can have varying symptoms. From this study, we make suggestions to vendors, operators, and systems designers.

MittOS provides operating system support to cut millisecond-level tail latencies for data-parallel applications. In MittOS, we advocate a new principle that operating system should quickly reject IOs that cannot be promptly served. To achieve this, MittOS exposes a fast rejecting SLO-aware interface wherein applications can provide their SLOs (e.g., IO deadlines). If MittOS predicts that the IO SLOs cannot be met, MittOS will promptly return EBUSY signal, allowing the application to failover (retry) to another less-busy node without waiting. We build MittOS within the storage stack (disk, SSD, and OS cache managements), but the principle is extensible to CPU and runtime memory managements as well. MittOS' no-wait approach helps reduce IO completion time up to 35% compared to wait-then-speculate approaches.

Flash storage has become the mainstream destination for storage users. However, SSDs do not always deliver the performance that users expect. The core culprit of flash performance instability is the well-known garbage collection (GC) process, which causes long delays as the SSD cannot serve (blocks) incoming I/Os, which then induces the long tail latency problem. We present tt F lash as a solution to this problem. tt F lash is a “tiny-tail” flash drive (SSD) that eliminates GC-induced tail latencies by circumventing GC-blocked I/Os with four novel strategies: plane-blocking GC, rotating GC, GC-tolerant read, and GC-tolerant flush. These four strategies leverage the timely combination of modern SSD internal technologies such as powerful controllers, parity-based redundancies, and capacitor-backed RAM. Our strategies are dependent on the use of intra-plane copyback operations. Through an extensive evaluation, we show that tt F lash comes significantly close to a “no-GC” scenario. Specifically, between the 99 and 99.99th percentiles, tt F lash is only 1.0 to 2.6× slower than the no-GC case, while a base approach suffers from 5–138× GC-induced slowdowns.

We conducted a cloud outage study (COS) of 32 popular Internet services. We analyzed 1247 headline news and public post-mortem reports that detail 597 unplanned outages that occurred within a 7-year span from 2009 to 2015. We analyzed outage duration, root causes, impacts, and fix procedures. This study reveals the broader availability landscape of modern cloud services and provides answers to why outages still take place even with pervasive redundancies.

We conduct a comprehensive study of development and deployment issues of six popular and important cloud systems (Hadoop MapReduce, HDFS, HBase, Cassandra, ZooKeeper and Flume). From the bug repositories, we review in total 21,399 submitted issues within a three-year period (2011-2014). Among these issues, we perform a deep analysis of 3655 "vital" issues (i.e., real issues affecting deployments) with a set of detailed classifications. We name the product of our one-year study Cloud Bug Study database (CbsDB) [9], with which we derive numerous interesting insights unique to cloud systems. To the best of our knowledge, our work is the largest bug study for cloud systems to date.

We highlight one often-overlooked cause of performance failure: limpware -- "limping" hardware whose performance degrades significantly compared to its specification. We report anecdotes of degraded disks and network components seen in large-scale production. To measure the system-level impact of limpware, we assembled limpbench, a set of benchmarks that combine data-intensive load and limpware injections. We benchmark five cloud systems (Hadoop, HDFS, ZooKeeper, Cassandra, and HBase) and find that limpware can severely impact distributed operations, nodes, and an entire cluster. From this, we introduce the concept of limplock, a situation where a system progresses slowly due to the presence of limpware and is not capable of failing over to healthy components. We show how each cloud system that we analyze can exhibit operation, node, and cluster limplock. We conclude that many cloud systems are not limpware tolerant.