M. Aron and P. Druschel, \Soft timers: ecient microsecond software timer support for network processing". ACM Trans. Comput. Syst. 18(3), pp. 197-228, Aug 2000.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of up to 1000 frames per second are used for recording high speed events, such as vehicle crash experiments [26] Similar high rates can also be expected for sampling sensors in various situations. Even higher rates are necessary in networking, for the implementation of ratebased transmission [25, 2]. Full utilization of a 100 Mb s Fast Ethernet with 1500 byte packets requires a packet to be transmitted every 120 s, i.e. 8333 times a second. On a gigabit link, the interval drops to 12 s, and the rate jumps up to 83,333 times a second. Increasing the clock interrupt rate may be expected to ....

....system, the Nemesis operating system for multimedia [15] and the KURT realtime system [25] The problem is that this may lead to high overhead if many timing events are requested with ne resolution. In soft timers the timing of system events is also not tied to periodic clock interrupts [2]. Instead, the system opportunistically makes use of convenient circumstances in order to provide higher resolution services. For example, on each return from a system call the system may check whether any timer has become ready, and re the respective events. As such opportunities occur at a much ....

[Article contains additional citation context not shown here]

M. Aron and P. Druschel, \Soft timers: ecient microsecond software timer support for network processing". ACM Trans. Comput. Syst. 18(3), pp. 197-228, Aug 2000.

....4.3, we present the programming interface provided by the MemNet system to applications. 3 Related Work OS mechanisms and policies speci cally tailored for servers have been proposed in [5, 13, 27] There have been other e orts aimed at improving server performance by avoiding interrupts [4, 21, 31] and separation of the OS from the application execution [24] In the Communication Services Platform (CSP) project [30] the authors suggest a system architecture for scalable cluster based servers, using dedicated network nodes and a VIA based SAN to tunnel TCP IP packets inside the cluster. ....

Aron, M., and Druschel, P. Soft timers: Ecient microsecond software timer support for network processing. ACM Transactions on Computer Systems 18, 3 (2000), 197-228.

....of interrupt processing. The system has to save the currently executed program s context as well as to restore its state at a later time. Measurements of the cost of this context switching show it to be in the 4 5 s range on both a 300MHz Pentium II system as well as for a 500MHz Pentium III CPU [25]. Unfortunately this latency is not simply a constant, but depends on the current state of the CPU, thus signi cantly a ecting the variability of the scheduling accuracy. Di erent scheduling implementation strategies for probe sending will be described and compared in section V. D.1 Real Time ....

....the param.h le) to 10000 from its original value of 100. As a result of this modi cation the idle load of the system increased to 5 , which corresponds to 5 s per periodic interrupt. This value agrees with the interrupt processing overhead measurement results published for Pentium processors in [25]. Besides increasing the idle load this increase unfortunately also increased the skew by a factor of 100, which is precisely the ratio between the new and original HZ values. This is due to integer arithmetic problems as the clock source code of the kernel is full of integer divisions by HZ. ....

M. Aron and P. Druschel, \Soft timers: ecient microsecond software timer support for network processing," Operating Systems Review, vol. 34, pp. 232-246, December 1999. Also in 17th ACM Symposium on Operating System Principles (SOSP'99).

....over the network and assign them to queues to be later handled by IP, TCP, UDP or other processes that constitute the network stack. If the end server is overloaded, it may start spending a higher percentage of time in processing network interrupts since interrupts have a higher priority [5] 6] [7]. If other resources like memory or CPU on the server are running low, these bu ers may be dropped before they get a chance to be serviced by the kernel s bottom half handler and the network stack. This phenomenon can be observed in Figure 7. Hence, there is need for a Bastion Host to regulate ....

Mohit Aron and Peter Druschel, \Soft timers: ecient microsecond software timer support for netw ork processing," in 17th GARG AND REDDY: POLICY BASED END SERVER RESOURCE REGULATION 11 ACM Symposium on Operating Systems Principles, December 1999, pp. 232-246.

....over the network and assign them to queues to be later handled by IP, TCP, UDP or other processes that constitute the network stack. If the end server is overloaded, it may start spending a higher percentage of time in processing network interrupts since interrupts have a higher priority [5] 6] [7]. If other resources like memory or CPU on the server are running low, these bu ers may be dropped before they get a chance to be serviced by the kernel s bottom half handler and the network stack. This phenomenon can be observed in Figure 6. These results underscore our earlier motivation for ....

M. Aron and P. Druschel, \Soft timers: ecient microsecond software timer support for netw ork processing," in 17th ACM Symposium on Operating Systems Principles, December 1999, pp. 232-246.

....over the network and assign them to queues to be later handled by IP, TCP, UDP or other processes that constitute the network stack. If the end server is overloaded, it may start spend 38 ing a higher percentage of time in processing network interrupts since interrupts have a higher priority [35, 36, 37]. If other resources like memory or CPU on the server are running low, these bu ers may be dropped before they get a chance to be serviced by the kernel s bottom half handler and the network stack. This phenomenon can be observed in Figures 10 and 11. The server spends all its time handling ....

Mohit Aron and Peter Druschel, \Soft timers: ecient microsecond software timer support for network processing," in 17th ACM Symposium on Operating Systems Principles, December 1999, pp. 232-246.

....calling context tree [3] while [15] uses sampling to reduce the cost of pro ling program values. These techniques are a specialized examples of the general technique proposed by our framework, that is, using sampling to reduce the overhead of a previously exhaustive instrumentation. Aron et al. [9] describes soft timers, an operating system facility that allows ecient processing of high frequency software events, by strategically scheduling them at times when overhead will be minimized. This is orthogonal to the goal of counter based sampling, which triggers high frequency samples to ....

M. Aron and P. Druschel. Soft timers: ecient microsecond software timer support for network processing. In In Proceedings of the 17th ACM Symposium on Operating Systems Principles (SOSP'99), pages 232-246, 1999.

....by Perkovic et al. 9] They describe an approach to support low overhead network polling using event ags similar to ours, but they mainly consider inserting this polling code into applications through source code manipulation. A technique to provide ecient timer support is soft timers [2], where the operating system is sprinkled with timer checks at places, where a timer handler can be red with low overhead. Soft timers can be used for ecient clocked polling, but the approach does not increase the responsiveness of an idle system. In scienti c parallel programs, the program ....

Mohit Aron and Peter Druschel. Soft timers: ecient microsecond software timer support for network processing. In Proceedings of the 17th Symposium on Operating Systems Principles, pages 232-246, Kiawah Island Resort, near Charleston, South Carolina, December 1999.

....use the i8254 Programmable Interval Timer (PIT) to generate interrupts every 500#s, and build a simple timeout system over that. Experiments demonstrate how this rather coarse grained timer is amply sucient for our purposes. Each interrupt causes a processing overhead of about 4#s on our hardware [2], thus causing about 1 CPU overhead on computational workloads. Other timeout mechanisms can be used in place of the i8254, if higher accuracy and lower overhead are desired. Some pentium class processors (mostly SMPs) have an on chip APIC that delivers negrained interrupts with an overhead of ....

....workloads. Other timeout mechanisms can be used in place of the i8254, if higher accuracy and lower overhead are desired. Some pentium class processors (mostly SMPs) have an on chip APIC that delivers negrained interrupts with an overhead of only 1 to 2#s per interrupt. Alternatively, soft timers [2] pose an extremely light weight alternative. 4. EXPERIMENTAL EVALUATION This section evaluates the anticipatory scheduling framework on a range of microbenchmarks and real workloads. We show that this transparentkernel level solution eliminates deceptive idleness, and achieves signi cant ....

M. Aron and P. Druschel. Soft timers: Ecient microsecond software timer support for network processing. In 17th ACM SOSP, Dec. 1999.

....We use the i8254 Programmable Interval Timer (PIT) to generate interrupts every 500 s, and build a simple timeout system over that. Experiments demonstrate how this rather inaccurate timer is amply sucient for our purposes. Each interrupt causes a processing overhead of about 4 s on our hardware [AD99] thus causing about 1 CPU overhead on computational workloads. Other timeout mechanisms can be used in place of the i8254, if higher accuracy is desired. Some pentium class processors (mostly SMPs) have an on chip APIC that delivers ne grained interrupts with an overhead of only 1 to 2 s per ....

....on computational workloads. Other timeout mechanisms can be used in place of the i8254, if higher accuracy is desired. Some pentium class processors (mostly SMPs) have an on chip APIC that delivers ne grained interrupts with an overhead of only 1 to 2 s per interrupt. Alternatively, soft timers [AD99] pose an extremely light weight alternative. 6.7.1 Tagged queueing in SCSI controllers The NWCS algorithm, as presented above, applies to IDE disks that have no additional queueing within the controller. It requires only one modi cation to work for SCSI disks with tagged queueing: the busy ....

M. Aron and P. Druschel. Soft timers: ecient microsecond software timer support for network processing. In Seventeenth ACM SOSP, Kiawah Island, SC, December 1999.

....use the i8254 Programmable Interval Timer (PIT) to generate interrupts every 500 s, and build a simple timeout system over that. Experiments demonstrate how this rather coarse grained timer is amply sucient for our purposes. Each interrupt causes a processing overhead of about 4 s on our hardware [2], thus causing about 1 CPU overhead on computational workloads. Other timeout mechanisms can be used in place of the i8254, if higher accuracy and lower overhead are desired. Some pentium class processors (mostly SMPs) have an on chip APIC that delivers negrained interrupts with an overhead of ....

....workloads. Other timeout mechanisms can be used in place of the i8254, if higher accuracy and lower overhead are desired. Some pentium class processors (mostly SMPs) have an on chip APIC that delivers negrained interrupts with an overhead of only 1 to 2 s per interrupt. Alternatively, soft timers [2] pose an extremely light weight alternative. 4. EXPERIMENTAL EVALUATION This section evaluates the anticipatory scheduling framework on a range of microbenchmarks and real workloads. We show that this transparent kernel level solution eliminates deceptive idleness, and achieves signi cant ....

M. Aron and P. Druschel. Soft timers: Ecient microsecond software timer support for network processing. In 17th ACM SOSP, Dec. 1999.

....that generates permits at a xed rate. Network packets are transmitted only after a permit is available for the packet. Therefore, packet bursts are limited by the capacity of the bucket, while the average transmission rate is governed by the rate at which permits are generated. Ecient mechanisms [10] have been designed in operating systems to support trac shaping at Gigabit packet transmission rates. The Virtual Clock [114] is a queuing discipline for network switches that is capable of a ording rate guarantees to ows. It involves an explicit ow setup phase where each source indicates its ....

M. Aron and P. Druschel. Soft timers: ecient microsecond software timer support for network processing. In Proceedings of the Seventeenth ACM Symposium on Operating Systems Principles, Kiawah Island, SC, Dec. 1999.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC