Thanks Rafael for your quick look at and all the time you spend for this! A /sys userspace knob will certainly not be enough for us. You'll need a tool installed fixing this. powertop on laptops or tuned on servers or a well hidden bootup quirk or whatsoever.
The patch I sent with this part: + if (acpi_gbl_FADT.preferred_profile == PM_PERFORMANCE_SERVER || + acpi_gbl_FADT.preferred_profile == PM_ENTERPRISE_SERVER) + return; and not touching the EBP value then should at least match most of our users and OEMs who want a "performance" setting out of the box and set this on purpose. Even nicer would be compile option to not touch this at all. On Thursday, March 21, 2019 11:18:01 PM CET Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <[email protected]> ... > + * > + * Second, on many systems the initial EPB value coming from the platform > + * firmware is 0 ('performance') and at least on some of them that is > because + * the platform firmware does not initialize EPB Why does the CPU not initialize this value to 6? That would allow OEMs/BIOS to also suggest an init value for the system. We should try to get microcode people or whoever is in charge to initialize this value "properly" if Intel thinks 6 is the correct init value. > at all with the > assumption that + * the OS will do that anyway. That sometimes is > problematic, as it may cause + * the system battery to drain too fast, for > example, so it is better to adjust + * it on CPU bring-up and if the > initial EPB value for a given CPU is 0, the + * kernel changes it to 6 > ('normal'). I have an idea to let the kernel more decide about such policies. It's a nice example that it makes sense to let the kernel set default values. But not unconditionally, according to what the system is intended to do. I wanted to do this for quite some time.., I hopefully find the time and motivation now. Thanks Rafael. Sorry for the somewhat rude sounding previous mail, that was not on purpose. You helped me quite a lot in the past and you obviously still do. Thomas
