Re: [tech-aia] RISC-V ACLINT specification is now hosted on RISC-V GitHub

Josh Scheid

On Fri, May 28, 2021 at 4:07 PM Jonathan Behrens <behrensj@...> wrote:

The main issue I see with the mtime synchronization code sample in the linked spec is that it doesn't do anything to address clock drift. The linked paper claims that CPU clocks can drift by 10 microseconds/second or more, so unless you have dedicated hardware to prevent drift (in which case why are you bothering with software at all?) you are very rapidly going to observe time readings that differ by more than one tick even if they start out consistent.

At least at the platform level, the requirement of a single reference clock for all timers in a "system" (thus preventing first-order drift) may be a desirable requirement.


Join { to automatically receive all group messages.