The sheer increase in network speed and the massive deployment of containerized applications in a Linux server has led to the consciousness that iptables, the current de-facto firewall in Linux, may not be able to cope with the current requirements particularly in terms of scalability in the number of rules. This paper presents an eBPF-based firewall, bpf-iptables, which emulates the iptables filtering semantic while guaranteeing higher throughput. We compare our implementation against the current version of iptables and other Linux firewalls, showing how it achieves a notable boost in terms of performance particularly when a high number of rules is involved. This result is achieved without requiring custom kernels or additional software frameworks (e.g., DPDK) that could not be allowed in some scenarios such as public data-centers.
Steady-state incremental constraints of manipulated variables play a vital role in making given steady-states satisfy physical limitations and avoiding drastic set-point changes. Nevertheless, some research reveals that the steady-state incremental constraints will make the given locally optimal economic steadystates diverge from the globally optimal economic steady-states. Therefore, a novel weighted local steady-state determination approach based on the globally optimal economic steady-states is presented in this paper. Firstly, the globally and locally optimal economic steady-states are both evaluated through considering and not considering steady-state incremental constraints. Then, the angle between them is evaluated and the closest local steady-state from the globally optimal economic steady-state is calculated. Subsequently, a new weighted local steady-state is evaluated by combining the locally optimal economic steady-state and the closest local steady-state, in which the weighting coefficient is carefully tuned based on the above-calculated angle. Finally, several simulations verify that the proposed method could effectively shorten the settling time of controlled systems and improve their economic performance.
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