Results 1 - 10
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401
Dealing with disaster: Surviving misbehaved kernel extensions
- In OSDI
, 1996
"... Today’s extensible operating systems allow applications to modify kernel behavior by providing mechanisms for application code to run in the kernel address space. The advantage of this approach is that it provides improved application flexibility and performance; the disadvantage is that buggy or ma ..."
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Cited by 276 (9 self)
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Today’s extensible operating systems allow applications to modify kernel behavior by providing mechanisms for application code to run in the kernel address space. The advantage of this approach is that it provides improved application flexibility and performance; the disadvantage is that buggy or malicious code can jeopardize the integrity of the kernel. It has been demonstrated that it is feasible to use safe languages, software fault isolation, or virtual memory protection to safeguard the main kernel. However, such protection mechanisms do not address the full range of problems, such as resource hoarding, that can arise when application code is introduced into the kernel. In this paper, we present an analysis of extension mechanisms in the VINO kernel. VINO uses software fault isolation as its safety mechanism and a lightweight transaction system to cope with resource-hoarding. We explain how these two mechanisms are sufficient to protect against a large class of errant or malicious extensions, and we quantify the overhead that this protection introduces. We find that while the overhead of these techniques is high relative to the cost of the extensions themselves, it is low relative to the benefits that extensibility brings.
A Feedback-driven Proportion Allocator for Real-Rate Scheduling
, 1999
"... In this paper we propose changing the decades-old practice of allocating CPU to threads based on priority to a scheme based on proportion and period. Our scheme allocates to each thread a percentage of CPU cycles over a period of time, and uses a feedback-based adaptive scheduler to assign automatic ..."
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Cited by 222 (27 self)
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In this paper we propose changing the decades-old practice of allocating CPU to threads based on priority to a scheme based on proportion and period. Our scheme allocates to each thread a percentage of CPU cycles over a period of time, and uses a feedback-based adaptive scheduler to assign automatically both proportion and period. Applications with known requirements, such as isochronous software devices, can bypass the adaptive scheduler by specifying their desired proportion and/or period. As a result, our scheme provides reservations to applications that need them, and the benefits of proportion and period to those that do not. Adaptive scheduling using proportion and period has several distinct benefits over either fixed or adaptive priority based schemes: finer grain control of allocation, lower variance in the amount of cycles allocated to a thread, and avoidance of accidental priority inversion and starvation, including defense against denial-of-service attacks. This paper descr...
Application performance and flexibility on Exokernel systems
- In Proceedings of the Sixteenth ACM Symposium on Operating Systems Principles
, 1997
"... The exokernel operating system architecture safely gives untrusted software efficient control over hardware and software resources by separating management from protection. This paper describes an exokernel system that allows specialized applications to achieve high performance without sacrificing t ..."
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Cited by 207 (10 self)
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The exokernel operating system architecture safely gives untrusted software efficient control over hardware and software resources by separating management from protection. This paper describes an exokernel system that allows specialized applications to achieve high performance without sacrificing the performance of unmodified UNIX programs. It evaluates the exokernel architecture by measuring end-to-end application performance on Xok, an exokernel for Intel x86-based computers, and by comparing Xok’s performance to the performance of two widely-used 4.4BSD UNIX systems (Free-BSD and OpenBSD). The results show that common unmodified UNIX applications can enjoy the benefits of exokernels: applications either perform comparably on Xok/ExOS and the BSD UNIXes, or perform significantly better. In addition, the results show that customized applications can benefit substantially from control over their resources (e.g., a factor of eight for a Web server). This paper also describes insights about the exokernel approach gained through building three different exokernel systems, and presents novel approaches to resource multiplexing. 1
Active Disks: Programming Model, Algorithms and Evaluation
, 1998
"... Several application and technology trends indicate that it might be both profitable and feasible to move computation closer to the data that it processes. In this paper, we evaluate Active Disk architectures which integrate significant processing power and memory into a disk drive and allow applicat ..."
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Cited by 202 (10 self)
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Several application and technology trends indicate that it might be both profitable and feasible to move computation closer to the data that it processes. In this paper, we evaluate Active Disk architectures which integrate significant processing power and memory into a disk drive and allow application-specific code to be downloaded and executed on the data that is being read from (written to) disk. The key idea is to o#oad bulk of the processing to the disk-resident processors and to use the host processor primarily for coordination, scheduling and combination of results from individual disks. To program Active Disks, we propose a stream-based programming model which allows disklets to be executed efficiently and safely. Simulation results for a suite of six algorithms from three application domains (commercial data warehouses, image processing and satellite data processing) indicate that for these algorithms, Active Disks outperform conventional-disk architectures.
On Implementing MPI-IO Portably and with High Performance
- In Proceedings of the 6th Workshop on I/O in Parallel and Distributed Systems
, 1999
"... We discuss the issues involved in implementing MPI-IO portably on multiple machines and file systems and also achieving high performance. One way to implement MPI-IO portably is to implement it on top of the basic Unix I/O functions (open, lseek, read, write, and close), which are themselves portabl ..."
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Cited by 196 (20 self)
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We discuss the issues involved in implementing MPI-IO portably on multiple machines and file systems and also achieving high performance. One way to implement MPI-IO portably is to implement it on top of the basic Unix I/O functions (open, lseek, read, write, and close), which are themselves portable. We argue that this approach has limitations in both functionality and performance. We instead advocatean implementation approach that combines a large portion of portable code and a small portion of code that is optimized separately for different machines and file systems. We have used such an approach to develop a high-performance, portable MPI-IO implementation, called ROMIO. In addition to basic I/O functionality, we consider the issues of supporting other MPI-IO features, such as 64-bit file sizes, noncontiguous accesses, collective I/O, asynchronous I/O, consistency and atomicity semantics, user-supplied hints, shared file pointers, portable data representation, and file preallocati...
Automatic Compiler-Inserted I/O Prefetching for Out-of-Core Applications
, 1996
"... Current operating systems offer poor performance when a numeric application's working set does not fit in main memory. As a result, programmers who wish to solve "out-of-core" problems efficiently are typically faced with the onerous task of rewriting an application to use explicit I/ ..."
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Cited by 162 (6 self)
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Current operating systems offer poor performance when a numeric application's working set does not fit in main memory. As a result, programmers who wish to solve "out-of-core" problems efficiently are typically faced with the onerous task of rewriting an application to use explicit I/O operations (e.g., read/write). In this paper, we propose and evaluate a fully-automatic technique which liberates the programmer from this task, provides high performance, and requires only minimal changes to current operating systems. In our scheme, the compiler provides the crucial information on future access patterns without burdening the programmer, the operating system supports non-binding prefetch and re- lease hints for managing I/O, and the operating sys- tem cooperates with a run-time layer to accelerate performance by adapting to dynamic behavior and minimizing prefetch overhead. This approach maintains the abstraction of unlimited virtual memory for the programmer, gives the compiler the flexibility to aggressively move prefetches back ahead of references, and gives the operating system the flexibility to arbitrate between the competing resource demands of multiple applications. We have implemented our scheme using the SUIF compiler and the Hurricane operating system. Our experimental results demonstrate that our fully-automatic scheme effectively hides the I/O latency in out-of- core versions of the entire NAS Parallel benchmark suite, thus resulting in speedups of roughly twofold for five of the eight applications, with one application speeding up by over threefold.
An analytical approach to file prefetching
- In Proceedings of USENIX 1997 Annual Technical Conference
, 1997
"... flei djdgcscolumbiaedu File prefetching is an eective technique for improving le access performance In this paper we present a le prefetching mechanism that is based on online analytic modeling of interesting system events and is transpar ent to higher levels The mechanism incorporated into a c ..."
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Cited by 139 (0 self)
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flei djdgcscolumbiaedu File prefetching is an eective technique for improving le access performance In this paper we present a le prefetching mechanism that is based on online analytic modeling of interesting system events and is transpar ent to higher levels The mechanism incorporated into a clients le cache manager seeks to build semantic structures called access trees that capture the corre lations between le accesses It then heuristically uses these structures to represent distinct le usage patterns and exploits them to prefetch les from a le server We show results of a simulation study and of a working im plementation Measurements suggest that our method can predict future le accesses with an accuracy around
Anticipatory scheduling: A disk scheduling framework to overcome deceptive idleness in synchronous I/O
, 2001
"... Disk schedulers in current operating systems are generally work-conserving, i.e., they schedule a request as son as the previous request has finished. Such schedulers often require multiple outstanding requests from each process to meet system-level goals of performance and quality of service. U ..."
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Cited by 138 (2 self)
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Disk schedulers in current operating systems are generally work-conserving, i.e., they schedule a request as son as the previous request has finished. Such schedulers often require multiple outstanding requests from each process to meet system-level goals of performance and quality of service. Unfortunately, many common applications issue disk read requests in a synchronous manna% interspersing successive requests with shor periods of computation. The scheduler chooses the next request too early; this induces deceptive idleness, a condition where the scheduler incorrectly assumes that the test request issuing process has no further requests, and becomes forced to switch to a toques? from another pro- Ce3S.
Model-Based Resource Provisioning in a Web Service Utility
- In Proceedings of the Fourth USENIX Symposium on Internet Technologies and Systems (USITS
, 2003
"... Rights to individual papers remain with the author or the author's employer. Permission is granted for noncommercial reproduction of the work for educational or research purposes. This copyright notice must be included in the reproduced paper. USENIX acknowledges all trademarks herein. ..."
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Cited by 131 (9 self)
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Rights to individual papers remain with the author or the author's employer. Permission is granted for noncommercial reproduction of the work for educational or research purposes. This copyright notice must be included in the reproduced paper. USENIX acknowledges all trademarks herein.
