On Tue, Jun 18, 2024 at 12:09:19PM -0500, Mario Limonciello wrote: > On 6/17/2024 21:54, Aaron Rainbolt wrote: > > acpi: Allow ignoring _OSC CPPC v2 bit via kernel parameter > > > > The _OSC is supposed to contain a bit indicating whether the hardware > > supports CPPC v2 or not. This bit is not always set, causing CPPC v2 to > > be considered absent. This results in severe single-core performance > > issues with the EEVDF scheduler. > > > > To work around this, provide a new kernel parameter, > > "processor.ignore_osc_cppc_bit", which may be used to ignore the _OSC > > CPPC v2 bit and act as if the bit was enabled. This allows CPPC to be > > properly detected even if not "enabled" by _OSC, allowing users with > > problematic hardware to obtain decent single-core performance. > > > > Tested-by: Michael Mikowski <mmikowski@xxxxxxxxxx> > > Signed-off-by: Aaron Rainbolt <arainbolt@xxxxxxxxxx> > > This sounds like a platform bug and if we do accept a patch like this I > think we need a lot more documentation about the situation. It is a platform bug, yes. See my previous email, https://lore.kernel.org/linux-acpi/d01b0a1f-bd33-47fe-ab41-43843d8a374f@xxxxxxxxxx/T/#u (I meant to send this email as a reply to that one, but failed to do so.) > Can you please share more information about your hardware: > 1) Manufacturer? Carbon Systems, models Iridium 14 and Iridium 16. > 2) CPU? Intel Core i5-13500H. > 3) Manufacturer firmware version? The systems use an AMI BIOS with version N.1.10CAR01 according to dmidecode. This is the latest BIOS available from the manufacturer. > 4) If it's AMD what's the AGESA version? Both affected systems are Intel-based and use heterogenous cores, not AMD. > And most importantly do you have the latest system firmware version from > your manufacturer? If not; please upgrade that first. We are using the latest firmware. (We're trying to work with the ODM to potentially get a firmware update, but since this affects more than just us and a firmware update may not be possible for everyone, this would likely be worth providing a kernel-level workaround for.) I can easily provide more detailed information - would the full output of 'dmidecode' and 'acpidump' be useful?
