Re: [sig-hypervisors] [RISC-V] [tech-unixplatformspec] SBI Debug Console Extension Proposal (Draft v1)
On Thu, Jun 2, 2022 at 1:29 PM Stefano Stabellini <stefano.stabellini@...> wrote:
On Thu, 2 Jun 2022, Vedvyas Shanbhogue via lists.riscv.org wrote:
Even though we all (me included) tend to think that slowing down something like this will be inconsequential to the time to boot and/or who cares how fast or slow is boot time, in the past I have found that to be a risky presumption in certain production environments where boot time matters (especially with frequent standing up of VMs from scratch). So a worthwhile sanity check question would be 1) what percentage of early boot time is spent writing to the console with per-string SBI calls, and 2) by what order of magnitude does that percentage inflate due to SBI calls for every individual character.
Starting at 1% and inflating to 10%-100% would not be good. Starting at 0.01% and inflating to 0.1-1% is likely acceptable.
Anup, care to try and ballpark #1 and #2 above?