We present Masstree, a fast key-value database designed for SMP machines. Masstree keeps all data in memory. Its main data structure is a trie-like concatenation of B+-trees, each of which handles a fixed-length slice of a variable-length key. This structure effectively handles arbitrary-length possiblybinary keys, including keys with long shared prefixes. +-tree fanout was chosen to minimize total DRAM delay when descending the tree and prefetching each tree node. Lookups use optimistic concurrency control, a read-copy-update-like technique, and do not write shared data structures; updates lock only affected nodes. Logging and checkpointing provide consistency and durability. Though some of these ideas appear elsewhere, Masstree is the first to combine them. We discuss design variants and their consequences.

The security of many applications relies on the kernel being secure, but history suggests that kernel vulnerabilities are routinely discovered and exploited. In particular, exploitable vulnerabilities in kernel modules are common. This paper proposes LXFI, a system which isolates kernel modules from the core kernel so that vulnerabilities in kernel modules cannot lead to a privilege escalation attack. To safely give kernel modules access to complex kernel APIs, LXFI introduces the notion of API integrity, which captures the set of contracts assumed by an interface. To partition the privileges within a shared module, LXFI introduces module principals. Programmers specify principals and API integrity rules through capabilities and annotations. Using a compiler plugin, LXFI instruments the generated code to grant, check, and transfer capabilities between modules, according to the programmer's annotations. An evaluation with Linux shows that the annotations required on kernel functions to support a new module are moderate, and that LXFI is able to prevent three known privilege-escalation vulnerabilities. Stress tests of a network driver module also show that isolating this module using LXFI does not hurt TCP throughput but reduces UDP throughput by 35%, and increases CPU utilization by 2.2-3.7x.

With the rapid advances of digital photography technology, high resolution video can be recorded using video camera for home entertainment and digital cinema. High end projector used for high resolution video display is bulky and expensive, only suitable for fixed installation, and prevents itself from being widely adopted. In this paper, we present one high resolution video display system using multiple projectors to replace the high end projector playback system. Our system is driven by single PC with PCI-E16 x interface and supports at least triple projectors, which is suitable for building surround video display system. It fully exploits the high bandwidth between CPU and graphics card, and efficiently plays back high resolution video of any format supported by commercial video player. We design geometric alignment and photometric correction methods to display the video content seamlessly on the planar display screen. Experimental results show that our system displays high resolution video at its full frame rate.