{"title":"The last CPU","authors":"J. Nider, Alexandra Fedorova","doi":"10.1145/3458336.3465291","DOIUrl":"https://doi.org/10.1145/3458336.3465291","url":null,"abstract":"Since the end of Dennard scaling and Moore's Law have been foreseen, specialized hardware has become the focus for continued scaling of application performance. Programmable accelerators such as smart memory, smart disks, and smart NICs are now being integrated into our systems. Many accelerators can be programmed to process their data autonomously and require little or no intervention during normal operation. In this way, entire applications are offloaded, leaving the CPU with the minimal responsibilities of initialization, coordination and error handling. We claim that these responsibilities can also be handled in simple hardware other than the CPU and that it is wasteful to use a CPU for these purposes. We explore the role and the structure of the OS in a system that has no CPU and demonstrate that all necessary functionality can be moved to other hardware. We show that almost all of the pieces for such a system design are already available today. The responsibilities of the operating system must be split between self-managing devices and a system bus that handles privileged operations.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117088048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deepti Raghavan, P. Levis, M. Zaharia, Irene Zhang
{"title":"Breakfast of champions: towards zero-copy serialization with NIC scatter-gather","authors":"Deepti Raghavan, P. Levis, M. Zaharia, Irene Zhang","doi":"10.1145/3458336.3465287","DOIUrl":"https://doi.org/10.1145/3458336.3465287","url":null,"abstract":"Microsecond I/O will make data serialization a major bottleneck for datacenter applications. Serialization is fundamentally about data movement: serialization libraries coalesce and flatten in-memory data structures into a single transmittable buffer. CPU-based serialization approaches will hit a performance limit due to data movement overheads and be unable to keep up with modern networks. We observe that widely deployed NICs possess scatter-gather capabilities that can be re-purposed to accelerate serialization's core task of coalescing and flattening in-memory data structures. It is possible to build a completely zero-copy, zero-allocation serialization library with commodity NICs. Doing so introduces many research challenges, including using the hardware capabilities efficiently for a wide variety of non-uniform data structures, making application memory available for zero-copy I/O, and ensuring memory safety.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128227299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sujin Park, I. Calciu, Taesoo Kim, Sanidhya Kashyap
{"title":"Contextual concurrency control","authors":"Sujin Park, I. Calciu, Taesoo Kim, Sanidhya Kashyap","doi":"10.1145/3458336.3465279","DOIUrl":"https://doi.org/10.1145/3458336.3465279","url":null,"abstract":"Kernel synchronization primitives are of paramount importance to achieving good performance and scalability for applications. However, they are usually invisible and out of the reach of application developers. Instead, kernel developers and synchronization experts make all the decisions regarding kernel lock design. In this paper, we propose contextual concurrency control (C3), a new paradigm that enables userspace applications to tune concurrency control in the kernel. C3 allows developers to change the behavior and parameters of kernel locks, to switch between different lock implementations and to dynamically profile one or multiple locks for a specific scenario of interest. To showcase this idea, we designed and implemented Concord, a framework that allows a privileged userspace process to modify kernel locks on the fly without re-compiling the existing code base. We performed a preliminary evaluation on two locks showing that Concord allows userspace tuning of kernel locks without incurring significant overhead.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125369907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"From warm to hot starts: leveraging runtimes for the serverless era","authors":"J. Carreira, Sumer Kohli, R. Bruno, Pedro Fonseca","doi":"10.1145/3458336.3465305","DOIUrl":"https://doi.org/10.1145/3458336.3465305","url":null,"abstract":"The serverless computing model leverages high-level languages, such as JavaScript and Java, to raise the level of abstraction for cloud programming. However, today's design of serverless computing platforms based on stateless short-lived functions leads to missed opportunities for modern runtimes to optimize serverless functions through techniques such as JIT compilation and code profiling. In this paper, we show that modern serverless platforms, such as AWS Lambda, do not fully leverage language runtime optimizations. We find that a significant number of function invocations running on warm containers are executed with unoptimized code (warm-starts), leading to orders of magnitude performance slowdowns. We explore the idea of exploiting the runtime knowledge spread throughout potentially thousands of nodes to profile and optimize code. To that end, we propose Ignite, a serverless platform that orchestrates runtimes across machines to run optimized code from the start (hot-start). We present evidence that runtime orchestration has the potential to greatly reduce cost and latency of serverless workloads by running optimized code across thousands of serverless functions.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116224997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Theano Stavrinos, Daniel S. Berger, Ethan Katz-Bassett, Wyatt Lloyd
{"title":"Don't be a blockhead: zoned namespaces make work on conventional SSDs obsolete","authors":"Theano Stavrinos, Daniel S. Berger, Ethan Katz-Bassett, Wyatt Lloyd","doi":"10.1145/3458336.3465300","DOIUrl":"https://doi.org/10.1145/3458336.3465300","url":null,"abstract":"Research on flash devices almost exclusively focuses on conventional SSDs, which expose a block interface. Industry, however, has standardized and is adopting Zoned Namespaces (ZNS) SSDs, which offer a new storage interface that dominates conventional SSDs. Continued research on conventional SSDs is thus a missed opportunity to unlock a step-change improvement in system performance by building on ZNS SSDs. We argue for an immediate and complete shift in research to ZNS SSDs and discuss research directions.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133436524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"User-defined cloud","authors":"Yiying Zhang, A. A. Sani, G. Xu","doi":"10.1145/3458336.3465304","DOIUrl":"https://doi.org/10.1145/3458336.3465304","url":null,"abstract":"Since its creation, cloud computing has always taken a provider-dictated approach, where cloud providers define and manage the cloud to accommodate the user needs they deem important. We propose \"User-Defined Cloud\", or UDC, a new cloud scheme that allows users to define their own \"clouds\", by defining hardware resource needs, system software features, and security requirements of their applications, and to do so without the need to build or manage low-level systems.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"71 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114050114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xudong Sun, L. Suresh, Aishwarya Ganesan, R. Alagappan, Michael Gasch, Lilia Tang, Tianyin Xu
{"title":"Reasoning about modern datacenter infrastructures using partial histories","authors":"Xudong Sun, L. Suresh, Aishwarya Ganesan, R. Alagappan, Michael Gasch, Lilia Tang, Tianyin Xu","doi":"10.1145/3458336.3465276","DOIUrl":"https://doi.org/10.1145/3458336.3465276","url":null,"abstract":"Modern datacenter infrastructures are increasingly architected as a cluster of loosely coupled services. The cluster states are typically maintained in a logically centralized, strongly consistent data store (e.g., ZooKeeper, Chubby and etcd), while the services learn about the evolving state by reading from the data store, or via a stream of notifications. However, it is challenging to ensure services are correct, even in the presence of failures, networking issues, and the inherent asynchrony of the distributed system. In this paper, we identify that partial histories can be used to effectively reason about correctness for individual services in such distributed infrastructure systems. That is, individual services make decisions based on observing only a subset of changes to the world around them. We show that partial histories, when applied to distributed infrastructures, have immense explanatory power and utility over the state of the art. We discuss the implications of partial histories and sketch tooling for reasoning about distributed infrastructure systems.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115601689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jialin Li, Samantha Miller, Danyang Zhuo, Ang Chen, Jon Howell, T. Anderson
{"title":"An incremental path towards a safer OS kernel","authors":"Jialin Li, Samantha Miller, Danyang Zhuo, Ang Chen, Jon Howell, T. Anderson","doi":"10.1145/3458336.3465277","DOIUrl":"https://doi.org/10.1145/3458336.3465277","url":null,"abstract":"Linux has become the de-facto operating system of our age, but its vulnerabilities are a constant threat to service availability, user privacy, and data integrity. While one might scrap Linux and start over, the cost of that would be prohibitive due to Linux's ubiquitous deployment. In this paper, we propose an alternative, incremental route to a safer Linux through proper modularization and gradual replacement module by module. We lay out the research challenges and potential solutions for this route, and discuss the open questions ahead.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114701086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kevin Loughlin, S. Saroiu, A. Wolman, Baris Kasikci
{"title":"Stop! Hammer time: rethinking our approach to rowhammer mitigations","authors":"Kevin Loughlin, S. Saroiu, A. Wolman, Baris Kasikci","doi":"10.1145/3458336.3465295","DOIUrl":"https://doi.org/10.1145/3458336.3465295","url":null,"abstract":"Rowhammer attacks exploit electromagnetic interference among nearby DRAM cells to flip bits, corrupting data and altering system behavior. Unfortunately, DRAM vendors have opted for a blackbox approach to preventing these bit flips, exposing little information about in-DRAM mitigations. Despite vendor claims that their mitigations prevent Rowhammer, recent work bypasses these defenses to corrupt data. Further work shows that the Rowhammer problem is actually worsening in emerging DRAM and posits that system-level support is needed to produce adaptable and scalable defenses. Accordingly, we argue that the systems community can and must drive a fundamental change in Rowhammer mitigation techniques. In the short term, cloud providers and CPU vendors must work together to supplement limited in-DRAM mitigations---ill-equipped to handle rising susceptibility---with their own mitigations. We propose novel hardware primitives in the CPU's integrated memory controller that would enable a variety of efficient software defenses, offering flexible safeguards against future attacks. In the long term, we assert that major consumers of DRAM must persuade DRAM vendors to provide precise information on their defenses, limitations, and necessary supplemental solutions.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"67 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120904655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nathan Pemberton, Johann Schleier-Smith, Joseph Gonzalez
{"title":"The RESTless cloud","authors":"Nathan Pemberton, Johann Schleier-Smith, Joseph Gonzalez","doi":"10.1145/3458336.3465280","DOIUrl":"https://doi.org/10.1145/3458336.3465280","url":null,"abstract":"Cloud provider APIs have emerged as the de facto operating system interface for the warehouse scale computers that comprise the public cloud. Like single-server operating systems, they provide the resource allocation, protection, communication paths, naming, and scheduling for these large machines. Cloud provider APIs also provide all sorts of things that operating systems do not, things like big data analytics, machine learning model training, or factory automation. Somewhere, lurking within this menagerie of services, there is an operating system interface to a really big computer, the computer that today's application developers target. This computer works nothing like a single server, yet it also isn't a dispersed distributed system like the internet. It is something in-between. Now is the time to distill and refine a coherent \"cloud system interface\" from the multitude of cloud provider APIs, preferably a portable one. In this paper we discuss what goes in, what stays out, and the principles that inform these decisions.","PeriodicalId":224944,"journal":{"name":"Proceedings of the Workshop on Hot Topics in Operating Systems","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127756680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}