Timothy Zhu

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In data centers, the IO path to storage is long and complex. It comprises many layers or "stages" with opaque interfaces between them. This makes it hard to enforce end-to-end policies that dictate a storage IO flow's performance (e.g., guarantee a tenant's IO bandwidth) and routing (e.g., route an untrusted VM's traffic through a sanitization middlebox).(More)
Everyone loves a large caching tier in their multi-tier cloud-based web service because it both alleviates database load and provides lower request latencies. Even when load drops severely, administrators are reluctant to scale down their caching tier. This paper makes the case that (i) scaling down the caching tier is viable with respect to performance,(More)
Meeting service level objectives (SLOs) for tail latency is an important and challenging open problem in cloud computing infrastructures. The challenges are exacerbated by burstiness in the workloads. This paper describes PriorityMeister -- a system that employs a combination of per-workload priorities and rate limits to provide tail latency QoS for shared(More)
<i>TetriSched</i> is a scheduler that works in tandem with a calendaring reservation system to continuously re-evaluate the immediate-term scheduling plan for all pending jobs (including those with reservations and best-effort jobs) on each scheduling cycle. <i>TetriSched</i> leverages information supplied by the reservation system about jobs' deadlines and(More)
The views and conclusions contained in this document are those of the author and should not be interpreted as representing the official policies, either expressed or implied, of any sponsoring institution, the U.S. government or any other entity. Abstract Dynamic capacity provisioning is a well studied approach to handling gradual changes in data center(More)
Tetrisched is a new scheduler that explicitly considers both job-specific preferences and estimated job runtimes in its allocation of resources. Combined, this information allows tetrisched to provide higher overall value to complex application mixes consolidated on heterogeneous collections of machines. Job-specific preferences, provided by tenants in the(More)
Meeting tail latency Service Level Objectives (SLOs) in shared cloud networks is both important and challenging. One primary challenge is determining limits on the multi-tenancy such that SLOs are met. Doing so involves estimating latency, which is difficult, especially when tenants exhibit bursty behavior as is common in production environments.(More)
The views and conclusions contained in this document are those of the author and should not be interpreted as representing the official policies, either expressed or implied, of any sponsoring institution, the U.S. government or any other entity. Abstract Dynamic capacity provisioning is a well studied approach to handling gradual changes in data center(More)
This paper provides theory and evidence on structured security governance, and how governance structure affects security design. We focus on two types of frictions that exist in addressing situations of financial distress—costly effort provision and risk shifting incentives.The main insights of the model are: (1) In a second-best world in which control over(More)
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