B. Fiedler, D. Schwyn, Constantin Gierczak-Galle, David A. Cock, Timothy Roscoe
The immense hardware complexity of modern computers, both mobile phones and datacenter servers, is a seemingly endless source of bugs and vulnerabilities in system software. Classical OSes cannot address this, since they only run on a small subset of the machine. The issue is interactions within the entire ensemble of firmware blobs, co-processors, and CPUs that we term the de facto OS. The current "whac-a-mole" approach will not solve this problem, nor will clean-slate redesign: it is simply not possible to replace some firmware components and the engineering effort is too great. Our response, instead, is to build a high-level model of exactly what a given real hardware and software platform consists of, and captures for the first time the necessary and assumed trust relationships between the software contexts executing on different components (CPUs, devices, etc.). This principled but pragmatic approach allows us to make rigorous statements about the hodgepodge of soft- and firmware at the heart of modern computers. We expect these statements to be, at first, depressingly weak, but it may be the only way to identify changes that provably increase the trustworthiness of a real system, and quantify the benefits of these changes.
{"title":"Putting out the hardware dumpster fire","authors":"B. Fiedler, D. Schwyn, Constantin Gierczak-Galle, David A. Cock, Timothy Roscoe","doi":"10.1145/3593856.3595903","DOIUrl":"https://doi.org/10.1145/3593856.3595903","url":null,"abstract":"The immense hardware complexity of modern computers, both mobile phones and datacenter servers, is a seemingly endless source of bugs and vulnerabilities in system software. Classical OSes cannot address this, since they only run on a small subset of the machine. The issue is interactions within the entire ensemble of firmware blobs, co-processors, and CPUs that we term the de facto OS. The current \"whac-a-mole\" approach will not solve this problem, nor will clean-slate redesign: it is simply not possible to replace some firmware components and the engineering effort is too great. Our response, instead, is to build a high-level model of exactly what a given real hardware and software platform consists of, and captures for the first time the necessary and assumed trust relationships between the software contexts executing on different components (CPUs, devices, etc.). This principled but pragmatic approach allows us to make rigorous statements about the hodgepodge of soft- and firmware at the heart of modern computers. We expect these statements to be, at first, depressingly weak, but it may be the only way to identify changes that provably increase the trustworthiness of a real system, and quantify the benefits of these changes.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"68 49","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134195593","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}
S. Ghemawat, Robert Grandl, S. Petrovic, Michael J. Whittaker, Parveen Patel, Ivan Posva, Amin Vahdat
When writing a distributed application, conventional wisdom says to split your application into separate services that can be rolled out independently. This approach is well-intentioned, but a microservices-based architecture like this often backfires, introducing challenges that counteract the benefits the architecture tries to achieve. Fundamentally, this is because microservices conflate logical boundaries (how code is written) with physical boundaries (how code is deployed). In this paper, we propose a different programming methodology that decouples the two in order to solve these challenges. With our approach, developers write their applications as logical monoliths, offload the decisions of how to distribute and run applications to an automated runtime, and deploy applications atomically. Our prototype implementation reduces application latency by up to 15× and reduces cost by up to 9× compared to the status quo.
{"title":"Towards Modern Development of Cloud Applications","authors":"S. Ghemawat, Robert Grandl, S. Petrovic, Michael J. Whittaker, Parveen Patel, Ivan Posva, Amin Vahdat","doi":"10.1145/3593856.3595909","DOIUrl":"https://doi.org/10.1145/3593856.3595909","url":null,"abstract":"When writing a distributed application, conventional wisdom says to split your application into separate services that can be rolled out independently. This approach is well-intentioned, but a microservices-based architecture like this often backfires, introducing challenges that counteract the benefits the architecture tries to achieve. Fundamentally, this is because microservices conflate logical boundaries (how code is written) with physical boundaries (how code is deployed). In this paper, we propose a different programming methodology that decouples the two in order to solve these challenges. With our approach, developers write their applications as logical monoliths, offload the decisions of how to distribute and run applications to an automated runtime, and deploy applications atomically. Our prototype implementation reduces application latency by up to 15× and reduces cost by up to 9× compared to the status quo.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126596004","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}
M. Roitzsch, Till Miemietz, Christian Von Elm, N. Asmussen
Our CPUs contain a compute instruction set, which regular applications use. But they also feature an intricate underworld of different CPU modes, combined with trap and exception handling to transition between these modes. These mechanisms are manifold and complex, yet the layering and functionality offered by the CPU modes is fixed. We have to take what CPU vendors provide, including potential security problems from unneeded modes. This paper explores the question, whether CPU modes could instead be defined entirely by software. We show how such a design would function and explore the advantages it enables. We believe that pushing all existing modes under a common design umbrella would enforce a cleaner structure and more control over exposed functionality. At the same time, the flexibility of software-defined modes enables interesting new use cases.
{"title":"Software-Defined CPU Modes","authors":"M. Roitzsch, Till Miemietz, Christian Von Elm, N. Asmussen","doi":"10.1145/3593856.3595894","DOIUrl":"https://doi.org/10.1145/3593856.3595894","url":null,"abstract":"Our CPUs contain a compute instruction set, which regular applications use. But they also feature an intricate underworld of different CPU modes, combined with trap and exception handling to transition between these modes. These mechanisms are manifold and complex, yet the layering and functionality offered by the CPU modes is fixed. We have to take what CPU vendors provide, including potential security problems from unneeded modes. This paper explores the question, whether CPU modes could instead be defined entirely by software. We show how such a design would function and explore the advantages it enables. We believe that pushing all existing modes under a common design umbrella would enforce a cleaner structure and more control over exposed functionality. At the same time, the flexibility of software-defined modes enables interesting new use cases.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"6 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134259362","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}
Zhihong Luo, Silvery Fu, Emmanuel Amaro, Amy Ousterhout, S. Ratnasamy, S. Shenker
Events that take 10s to 100s of ns like cache misses increasingly cause CPU stalls. However, hiding the latency of these events is challenging: hardware mechanisms suffer from the lack of flexibility, whereas prior software mechanisms fall short due to large overhead and limited event visibility. In this paper, we argue that with a combination of two emerging techniques - light-weight coroutines and sample-based profiling, hiding these events in software is within reach.
{"title":"Out of Hand for Hardware? Within Reach for Software!","authors":"Zhihong Luo, Silvery Fu, Emmanuel Amaro, Amy Ousterhout, S. Ratnasamy, S. Shenker","doi":"10.1145/3593856.3595898","DOIUrl":"https://doi.org/10.1145/3593856.3595898","url":null,"abstract":"Events that take 10s to 100s of ns like cache misses increasingly cause CPU stalls. However, hiding the latency of these events is challenging: hardware mechanisms suffer from the lack of flexibility, whereas prior software mechanisms fall short due to large overhead and limited event visibility. In this paper, we argue that with a combination of two emerging techniques - light-weight coroutines and sample-based profiling, hiding these events in software is within reach.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133268010","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}
Ruihao Li, Qinzhe Wu, K. Kavi, Gayatri Mehta, N. Yadwadkar, L. John
Memory allocation and management have a significant impact on performance and energy of modern applications. We observe that performance can vary by as much as 72% in some applications based on which memory allocator is used. Many current allocators are multi-threaded to support concurrent allocation requests from different threads. However, such multi-threading comes at the cost of maintaining complex metadata that is tightly coupled and intertwined with user data. When memory management functions and other user programs run on the same core, the metadata used by management functions may pollute the processor caches and other resources. In this paper, we make a case for offloading memory allocation (and other similar management functions) from main processing cores to other processing units to boost performance, reduce energy consumption, and customize services to specific applications or application domains. To offload these multi-threaded fine-granularity functions, we propose to decouple the metadata of these functions from the rest of application data to reduce the overhead of inter-thread metadata synchronization. We draw attention to the following key questions to realize this opportunity: (a) What are the tradeoffs and challenges in offloading memory allocation to a dedicated core? (b) Should we use general-purpose cores or special-purpose cores for executing critical system management functions? (c) Can this methodology apply to heterogeneous systems (e.g., with GPUs, accelerators) and other service functions as well?
{"title":"NextGen-Malloc: Giving Memory Allocator Its Own Room in the House","authors":"Ruihao Li, Qinzhe Wu, K. Kavi, Gayatri Mehta, N. Yadwadkar, L. John","doi":"10.1145/3593856.3595911","DOIUrl":"https://doi.org/10.1145/3593856.3595911","url":null,"abstract":"Memory allocation and management have a significant impact on performance and energy of modern applications. We observe that performance can vary by as much as 72% in some applications based on which memory allocator is used. Many current allocators are multi-threaded to support concurrent allocation requests from different threads. However, such multi-threading comes at the cost of maintaining complex metadata that is tightly coupled and intertwined with user data. When memory management functions and other user programs run on the same core, the metadata used by management functions may pollute the processor caches and other resources. In this paper, we make a case for offloading memory allocation (and other similar management functions) from main processing cores to other processing units to boost performance, reduce energy consumption, and customize services to specific applications or application domains. To offload these multi-threaded fine-granularity functions, we propose to decouple the metadata of these functions from the rest of application data to reduce the overhead of inter-thread metadata synchronization. We draw attention to the following key questions to realize this opportunity: (a) What are the tradeoffs and challenges in offloading memory allocation to a dedicated core? (b) Should we use general-purpose cores or special-purpose cores for executing critical system management functions? (c) Can this methodology apply to heterogeneous systems (e.g., with GPUs, accelerators) and other service functions as well?","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124522436","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}
Juncheng Yang, Zimeng Qiu, Yazhuo Zhang, Yao Yue, K. V. Rashmi
LRU has been the basis of cache eviction algorithms for decades, with a plethora of innovations on improving LRU's miss ratio and throughput. While it is well-known that FIFO-based eviction algorithms provide significantly better throughput and scalability, they lag behind LRU on miss ratio, thus, cache efficiency. We performed a large-scale simulation study using 5307 block and web cache workloads collected in the past two decades. We find that contrary to what common wisdom suggests, some FIFO-based algorithms, such as FIFO-Reinsertion (or CLOCK), are, in fact, more efficient (have a lower miss ratio) than LRU. Moreover, we find that qick demotion --- evicting most new objects very quickly --- is critical for cache efficiency. We show that when enhanced by qick demotion, not only can state-of-the-art algorithms be more efficient, a simple FIFO-based algorithm can outperform five complex state-of-the-art in terms of miss ratio.
{"title":"FIFO can be Better than LRU: the Power of Lazy Promotion and Quick Demotion","authors":"Juncheng Yang, Zimeng Qiu, Yazhuo Zhang, Yao Yue, K. V. Rashmi","doi":"10.1145/3593856.3595887","DOIUrl":"https://doi.org/10.1145/3593856.3595887","url":null,"abstract":"LRU has been the basis of cache eviction algorithms for decades, with a plethora of innovations on improving LRU's miss ratio and throughput. While it is well-known that FIFO-based eviction algorithms provide significantly better throughput and scalability, they lag behind LRU on miss ratio, thus, cache efficiency. We performed a large-scale simulation study using 5307 block and web cache workloads collected in the past two decades. We find that contrary to what common wisdom suggests, some FIFO-based algorithms, such as FIFO-Reinsertion (or CLOCK), are, in fact, more efficient (have a lower miss ratio) than LRU. Moreover, we find that qick demotion --- evicting most new objects very quickly --- is critical for cache efficiency. We show that when enhanced by qick demotion, not only can state-of-the-art algorithms be more efficient, a simple FIFO-based algorithm can outperform five complex state-of-the-art in terms of miss ratio.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130759424","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}
Emerging memory fabrics and the resulting composable infrastructures have fundamentally challenged our conventional wisdom on how to build efficient rack/cluster-scale systems atop. This position paper proposes a new computing paradigm-called Fabric-Centric Computing (FCC)-that views the memory fabric as a first-class citizen to instantiate, orchestrate, and reclaim computations over composable infrastructures. We describe its design principles, report our early experiences, and discuss a new intermediate system stack proposal that harnesses the uniqueness of this cluster interconnect and realizes the vision of FCC.
{"title":"Fabric-Centric Computing","authors":"Ming Liu","doi":"10.1145/3593856.3595907","DOIUrl":"https://doi.org/10.1145/3593856.3595907","url":null,"abstract":"Emerging memory fabrics and the resulting composable infrastructures have fundamentally challenged our conventional wisdom on how to build efficient rack/cluster-scale systems atop. This position paper proposes a new computing paradigm-called Fabric-Centric Computing (FCC)-that views the memory fabric as a first-class citizen to instantiate, orchestrate, and reclaim computations over composable infrastructures. We describe its design principles, report our early experiences, and discuss a new intermediate system stack proposal that harnesses the uniqueness of this cluster interconnect and realizes the vision of FCC.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114141364","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}
Farbod Shahinfar, S. Miano, G. Siracusano, R. Bifulco, Aurojit Panda, G. Antichi
BPF support in Linux has made kernel extensions easier. Recent efforts have shown that using BPF to offload portions of server applications, e.g., memcached and service proxies, can improve application performance and efficiency. However, thus far, the community has not looked at the question of what parts of an application should be offloaded? This paper first shows that blindly offloading application functionality to the kernel is neither beneficial nor desirable, and care must be taken when deciding what to offload. Furthermore, when deciding what to offload, developers must consider not just the application, but also the workload being handled, and the kernel being targetted, Therefore, we advocate automating this decision process in a compiler, that can analyze application code, and produce two executables, a kernel offload and a userspace program, that jointly implement the application's functionality. This paper discusses the challenges that must be addressed to build such a compiler, and why they can be feasibly addressed.
{"title":"Automatic Kernel Offload Using BPF","authors":"Farbod Shahinfar, S. Miano, G. Siracusano, R. Bifulco, Aurojit Panda, G. Antichi","doi":"10.1145/3593856.3595888","DOIUrl":"https://doi.org/10.1145/3593856.3595888","url":null,"abstract":"BPF support in Linux has made kernel extensions easier. Recent efforts have shown that using BPF to offload portions of server applications, e.g., memcached and service proxies, can improve application performance and efficiency. However, thus far, the community has not looked at the question of what parts of an application should be offloaded? This paper first shows that blindly offloading application functionality to the kernel is neither beneficial nor desirable, and care must be taken when deciding what to offload. Furthermore, when deciding what to offload, developers must consider not just the application, but also the workload being handled, and the kernel being targetted, Therefore, we advocate automating this decision process in a compiler, that can analyze application code, and produce two executables, a kernel offload and a userspace program, that jointly implement the application's functionality. This paper discusses the challenges that must be addressed to build such a compiler, and why they can be feasibly addressed.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129173052","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}
There have been many recent advances in enforcing finegrained access control for database-backed applications. However, operators face significant challenges both before and after an enforcement mechanism has been deployed. We identify three such challenges beyond enforcement and discuss possible solutions.
{"title":"Access Control for Database Applications: Beyond Policy Enforcement","authors":"Wen Zhang, Aurojit Panda, S. Shenker","doi":"10.1145/3593856.3595905","DOIUrl":"https://doi.org/10.1145/3593856.3595905","url":null,"abstract":"There have been many recent advances in enforcing finegrained access control for database-backed applications. However, operators face significant challenges both before and after an enforcement mechanism has been deployed. We identify three such challenges beyond enforcement and discuss possible solutions.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116990170","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}
Christoph Anneser, Lukas Vogel, F. Gruber, Maximilian Bandle, Jana Giceva
With full resource disaggregation on the horizon, it is unclear what the most suitable programming model is that enables dataflow developers to fully harvest the potential that recent hardware developments offer. In our vision, we propose to raise the abstraction level to allow developers to primarily reason about their dataflow and the requirements that need to be met by the underlying system in a declarative fashion. Underneath, the system works with typed memory regions and uses the notion of ownership that allows for more flexible memory management across the different compute devices and the tasks mapped onto them. This requires a holistic approach that crosses multiple layers of the system stack, opening exciting systems research questions.
{"title":"Programming Fully Disaggregated Systems","authors":"Christoph Anneser, Lukas Vogel, F. Gruber, Maximilian Bandle, Jana Giceva","doi":"10.1145/3593856.3595889","DOIUrl":"https://doi.org/10.1145/3593856.3595889","url":null,"abstract":"With full resource disaggregation on the horizon, it is unclear what the most suitable programming model is that enables dataflow developers to fully harvest the potential that recent hardware developments offer. In our vision, we propose to raise the abstraction level to allow developers to primarily reason about their dataflow and the requirements that need to be met by the underlying system in a declarative fashion. Underneath, the system works with typed memory regions and uses the notion of ownership that allows for more flexible memory management across the different compute devices and the tasks mapped onto them. This requires a holistic approach that crosses multiple layers of the system stack, opening exciting systems research questions.","PeriodicalId":330470,"journal":{"name":"Proceedings of the 19th Workshop on Hot Topics in Operating Systems","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132266212","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}
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