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stevenpusser
Status: Contributor
Joined: 14 Jan 2017
Posts: 89
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Yes, backported and installed it last night, and it is using less CPU at idle than 4.17-9 on my i7-8750H, very close to what a backported Debian 4.17.8 kernel reports using, and battery life seems better.
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damentz
Status: Assistant
Joined: 09 Sep 2008
Posts: 1122
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That's good news, thanks for the feedback.
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pyjujiop
Status: Curious
Joined: 26 Jul 2018
Posts: 5
Location: Mount Airy, NC
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:: damentz wrote ::
Sorry for the delay, I've been periodically trying different settings, some that require me to recompile the kernel. One that made a difference on a laptop of mine was to disable nohz entirely.

Can you try booting with the kernel parameter, nohz=n, from your boot manager? The consequence of this setting means that the kernel will interrupt the processor every millisecond even while idle. In powertop you'll see lines like this, especially while idle:

:: Code ::
             12.8 ms/s     586.9        Timer          tick_sched_timer


On my Latitude, I went from 1.5-2.5ghz using 0.9 volts in i7z down to 0.7 volts under 1ghz while sitting at the desktop with minimal applications open. As a bonus, my own CPU usage is lower.

Can you confirm? I want to make sure this is not a hardware specific quirk. I also have another machine I need to test this with but I'll get to that in about 10 hours.


This is the first time I've been back in several days, and I just saw this post and the fact that you'd put the tweak in the new kernel.

I booted to 4.17.0.14 (I had been using the stock kernel for a week) and it seems to have worked. Conky is reporting CPU frequencies within the normal range of this processor, rather than staying stuck between 3.9 and 4.0 GHz.

Thanks for working on it, but no apologies are necessary. Your kernel helped me get linux-PHC going on an old Inspiron 1545 (running Mint 19) so I could stick a cheap E8435 in there and get it to run a little below T9900 voltages. After that success, I decided to try liquorix on the desktop, too, which is what prompted this thread to start with.
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