Re: [PATCH] x86: intel_epb: Add earlyparam option to keep bias at performance

Jack Allister
2023-12-05T10:23:17Z

> This is fundamentally a hack.

I do not totally agree that this is a hack, the setting of it to the
ENERGY_PERF_BIAS_NORMAL is an equivalent workaround which is used for
systems where the platform firmware has not configured it as expected
for laptops etc. and that is already present.

> It sounds like you want the system default to be at
> ENERGY_PERF_BIAS_PERFORMANCE. You also mentioned that this was done "on
> kernel boot". How did you do that, exactly? Shouldn't that "on kernel
> boot" action be reflected over here rather than introducing another
> command-line parameter?

As Paul has mentioned, we perform live-updates of the host kernel running
on servers. This is done while virtual machines are still running so that
there is no perceived downtime for the guest/customer. This requires a
kexec into the new kernel and there are specific areas such as PCI device
enumeration which can take a substantial amount of time in it's current
form and can be perceived as downtime while the kernel is loading.

> Shouldn't that "on kernel
> boot" action be reflected over here rather than introducing another
> command-line parameter?

A kernel parameter may not be the most elegant solution, would a proposal
for a kernel build configuration be a bit more suitable?