Fast Privileged Function Calls

Research output: Contribution to conferencesPaperContributedpeer-review

Contributors

Abstract

We are approaching a world, where the CPU merely orchestrates a plethora of specialized devices such as accelerators, RDMA NICs, or non-volatile memory (NVM). Such devices operate by mapping their internal memory directly into an application’s address space for fast, low-latency access. With the latency of modern I/O devices low enough to make traditional system calls a performance bottleneck, kernel interaction has no place on the data path of microsecond-scale systems. However, kernel bypass prevents the
OS from controlling and supervising access to the hardware.

This paper tries to make a step back by bringing the OS to the critical path again, but with a reduced performance penalty. We pick up on previous ideas for reducing the cost of kernel interaction and propose the fastcall space, a new layer in the traditional OS architecture that hosts specialized and quickly accessible OS functions called fastcalls. Fastcalls can stay on the critical path of a microsecond-scale application because the invocation of fastcall-space functionality is up to 15 times faster than calling kernel functions from user space. We present and evaluate a prototype implementation of the fastcall framework and thereby show how much the overhead of calling into privileged mode can be reduced while using standard CPU features.

Details

Original languageEnglish
Publication statusPublished - 5 Apr 2022
Peer-reviewedYes

Workshop

TitleSystems for Post-Moore Architectures 2022
Abbreviated titleSPMA
Conference number
Duration5 April 2022
Website
Degree of recognitionInternational event
Location
CityRennes
CountryFrance