A microkernel api for fine-grained decomposition

Microkernel-based operating systems typically require spe-cial attention to issues that otherwise arise only in dis-tributed systems. The resulting extra code degrades per-formance and increases development effort, severely limiting decomposition granularity. We present a new microkernel design that enables OS devel-opers to decompose systems into very fine-grained servers. We avoid the typical obstacles by defining servers as light-weight, passive objects. We replace complex IPC mecha-nisms by a simple function-call approach, and our passive, module-like server model obviates the need to create threads in every server. Server code is compiled into small self-contained files, which can be loaded into the same address space (for speed) or different address spaces (for safety). For evaluation, we have developed a kernel according to our design, and a networking-capable multi-server system on top. Each driver is a separate server, and the networking stack is split into individual layers. Benchmarks on IA-32 hardware indicate promising results regarding server granu-larity and performance. 1