Thesis Defense: The Benefits and Costs of Writing a POSIX Kernel in a High-Level Language

Speaker: Cody Cutler , CSAIL

Date: Thursday, May 02, 2019

Time: 2:00 PM to 3:00 PM

Public: Yes

Location: 32-D463 (Star)

Event Type: Thesis Defense

Room Description:

Host:

Contact: Tej Chajed, tchajed@mit.edu

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Reminders to: seminars@csail.mit.edu

Reminder Subject: TALK: Thesis Defense: The Benefits and Costs of Writing a POSIX Kernel in a High-Level Language

This dissertation presents an evaluation of the use of a high-level language (HLL) with garbage collection to implement a monolithic POSIX-style kernel. The goal is to explore if it is reasonable to use an HLL instead of C for such kernels, by examining performance costs, implementation challenges, and programmability and safety benefits.

The dissertation contributes Biscuit, a kernel written in Go that implements enough of POSIX (virtual memory, mmap, TCP/IP sockets, a logging file system, poll, etc.) to execute significant applications. Biscuit makes liberal use of Go's HLL features (closures, channels, maps, interfaces, garbage collected heap allocation), which subjectively made programming easier. The most challenging puzzle was handling the possibility of running out of kernel heap memory; Biscuit benefited from the analyzability of Go source to address this challenge.

On a set of kernel-intensive benchmarks (including NGINX and Redis) the fraction of kernel CPU time Biscuit spends on HLL features (primarily garbage collection and thread stack expansion checks) ranges up to 13%. The longest single GC-related pause suffered by NGINX was 115 microseconds; the longest observed sum of GC delays to a complete NGINX client request was 600 microseconds. In experiments comparing nearly identical system call, page fault, and context switch code paths written in Go and C, the Go version was 5% to 15% slower.

Research Areas:
Systems & Networking

Impact Areas:

This event is not part of a series.

Created by Tej Chajed Email at Thursday, April 25, 2019 at 3:08 PM.