A Fix Is Out For The Intel Ice Lake Performance Drop On Linux With The Dell XPS 7390

[phoronix]

Phoronix: A Fix Is Out For The Intel Ice Lake Performance Drop On Linux With The Dell XPS 7390

Earlier this week I highlighted the Dell XPS 7390 "Ice Lake" ultrabook seeing a big performance drop on recent versions of the Linux kernel. Intel engineers seem to have sorted it out and now have a solution in place, which affects those running Linux 5.4 or newer...

http://www.phoronix.com/scan.php?page=news_item&px=Ice-Lake-Linux-Thermal-Fix-7390

[stormcrow]

The logic in the given explanation makes my brain cramp. Over engineer thermald so it doesn't accept an "invalid" thermal/power entry from the kernel... but don't fix the incorrect entries in the kernel's ACPI tables that are causing the problem to begin with... Then the question is how does thermald know if what's coming from the kernel is invalid, as information out of the kernel is supposed to be canonical. Why does this smell like an Intel solution?

Or am I reading this wrong and the kernel is picking up incorrect values off the hardware and passing them to thermald?

[smitty3268]

Or am I reading this wrong and the kernel is picking up incorrect values off the hardware and passing them to thermald?

I believe the tables are in firmware, so the kernel is just reading the values.

[Girolamo_Cavazzoni]

binary debacle

Made my day.

[Shtirlic]

Simple fix and do not use thermald, use

 /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq

and

scaling_max_freq

and rapl limits

cat /etc/tmpfiles.d/power_limit.conf
w /sys/devices/virtual/powercap/intel-rapl-mmio/intel-rapl-mmio:0/constraint_0_power_limit_uw - - - - 35000000

[DanL]

So.. Dell needs to fix its buggy BIOS/EFI?

[kcrudup]

So.. Dell needs to fix its buggy BIOS/EFI?

Pretty much; but I'm not holding my breath. That being said, a BIOS update went out on March 26th for the 2-in-1s that fixed one of the RAPL counters going away after a reboot, and may have fixed this issue, too.

... and now I know why I wasn't affected, as I'd put in the other thread; my 7390 2-in-1's thermal solution works well enough on it's own that I "systemctl mask"ed out thermald a long time ago, and even use a utility called "Throttled" to bump up the max Tdp when on AC.

[ermo]

So intel is having to jump through all sorts of hoops to avoid getting blamed for sub-optimal ${VENDOR} UEFI settings/QA?

Wow. That's ... a bit unfair, isn't it?

[Teggs]

So.. Dell needs to fix its buggy BIOS/EFI?

No doubt. Maybe Intel didn't trust that would happen. Or Intel is acting like a parent of not-too-bright children and just coding away the consequences in case vendors screw up like that in future.

[kcrudup]

So.. Dell needs to fix its buggy BIOS/EFI?

Eh, I'll bet Dell/Intel are like "Hey- it works in Windows; ship it!" ... and TBH, I get it.