To serve users quickly, Web service providers build infrastructure closer to clients and use multi-stage transport connections. Although these changes reduce client-perceived round-trip times, TCP’s current mechanisms fundamentally limit latency improvements. We performed a measurement study of a large Webservice provider and found that, while connections with no loss complete close to the ideal latency of one round-trip time, TCP’s timeoutdriven recovery causes transfers with loss to take five times longer on average. Inthispaper, wepresentthedesignofnovellossrecoverymechanisms for TCP that judiciously use redundant transmissions to minimize timeout-driven recovery. Proactive, Reactive, and Corrective are three qualitatively-different, easily-deployable mechanisms that (1) proactively recover from losses, (2) recover from them as quickly as possible, and (3) reconstruct packets to mask loss. Crucially, the mechanisms are compatible both with middleboxes and with TCP’s existing congestion control and loss recovery. Our large-scale experiments on Google’s production network that serves billions of flows demonstrate a 23 % decrease in the mean and47 % in99thpercentile latencyover today’s TCP. Categories andSubject Descriptors

To serve users quickly, Web service providers build infrastruc-ture closer to clients and use multi-stage transport connections. Although these changes reduce client-perceived round-trip times, TCP’s current mechanisms fundamentally limit latency improve-ments. We performed a measurement study of a large Web service provider and found that, while connections with no loss complete close to the ideal latency of one round-trip time, TCP’s timeout-driven recovery causes transfers with loss to take five times longer on average. In this paper, we present the design of novel loss recovery mech-anisms for TCP that judiciously use redundant transmissions to minimize timeout-driven recovery. Proactive, Reactive, and Cor-rective are three qualitatively-different, easily-deployable mecha-nisms that (1) proactively recover from losses, (2) recover from them as quickly as possible, and (3) reconstruct packets to mask loss. Crucially, the mechanisms are compatible both with mid-dleboxes and with TCP’s existing congestion control and loss re-covery. Our large-scale experiments on Google’s production net-work that serves billions of flows demonstrate a 23 % decrease in the mean and 47 % in 99th percentile latency over today’s TCP.

ABSTRACT We propose the concept of gentle acoustic crosstalk cancelation, which aims at reducing the crosstalk between a loudspeaker and the listener's contralateral ear instead of eliminating it completely as aggressive methods intend to do. The expected benefit is higher robustness and a

Lactating females express rapid extremes in behavior, ranging from gentle nurturance toward offspring to fiercely protective aggression against intruders. Although males often behave aggressively against intruders, female rodents usually express aggression only when rearing and protecting pups

that minimizes SRT within the constraints set by MCRT. For aggressively-washed filters, where MCRT and SRT are virtually equivalent, this means extending the backwash interval until the internal loading attenuates nitrification. In gently-washed filters, where MCRT is independent of SRT, backwash protocol

connection in order to distinguish between congestion-induced and non-congestion-induced packet losses. (b) LIMD/H reacts gently to non-congestion-induced losses and aggressively to congestion-induced losses, thereby achieving high efficiency, fairness, as well as quick reaction to the onset of congestion

Submitted to EuroSys 2009. General-purpose operating systems not only fail to provide adaptive applications the information they need to intelli-gently adapt, but also schedule resources in such a way that were applications to aggressively adapt, resources would be inappropriately scheduled

Aggressiveness and violence in schools are concerns that educators have to address. Using a random method of sampling, this study focused on six secondary schools located in the Chicago Public Schools System. Each school's administrator was interviewed, and two teachers at the school were also

limitation. This result was central to an explanation of why differing optimal backwash intervals in gently- and aggressively-washed filters are related to: (1) differences in harvest fraction, which fixes the relationship between backwash interval and interstitial solids concentration and (2) differences

aggressively when they enter the most profitable segment, quite gently when they enter the least profitable segment and moderately aggressive when they enter the entire market. JEL Classification: D43, D83