Re: [tech-aia] RISC-V ACLINT specification is now hosted on RISC-V GitHub
Jonathan Behrens <behrensj@...>
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If you're interested in reading about pure software approaches to clock synchronization, I recommend looking at https://www.usenix.org/conference/nsdi18/presentation/geng. They focus on synchronizing clocks between different servers in the same datacenter which if anything is a harder problem.
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.
On Fri, May 28, 2021 at 5:44 PM Josh Scheid via lists.riscv.org <jscheid=ventanamicro.com@...> wrote: