Samsung Introduces "LAB" Linux Frequency Governor

[phoronix]

Phoronix: Samsung Introduces "LAB" Linux Frequency Governor

Samsung developers last week provided patches for a new cpufreq governor dubbed "LAB", or the "Legacy Application Boost", for the Linux kernel...

http://www.phoronix.com/vr.php?view=MTM0NzI

[frign]

That won't work!

That won't work out as the Samsung engineers expected.
It is a common misconception the powersave governor actually runs more efficient than ondemand.
The opposite is true: Running at a lower clockrate increases the time until the CPU can jump back into Idle state, which in turn increases the load-time and energy consumption.

So, when the Samsung engineers want to lower the frequency in case mutliple cores are under heavy load, the frequency would effectively be lowered when the system is under heavy, parallelized load
, effectively increasing the load time.

This is not effective.

[Sonadow]

It reduces the heat output tremendously.

Have you ever tried to run Linux on a notebook using a full AMD stack (AMD processor + AMD graphics cards + AMD northbridge) without forcing the powersave govenor to be active at all times? You can literally soften a pencil eraser enough to remould it after putting it behind the notebook's vents.

I speak from personal experience.

[GreatEmerald]

It reduces the heat output tremendously.

Have you ever tried to run Linux on a notebook using a full AMD stack (AMD processor + AMD graphics cards + AMD northbridge) without forcing the powersave govenor to be active at all times? You can literally soften a pencil eraser enough to remould it after putting it behind the notebook's vents.

I speak from personal experience.

My observations as well. Anything other than the powersave governor makes my HTPC fry itself once it tries to do more or less anything that is remotely demanding (due to fairly low air flow capability). With powersave, it never reaches dangerous temperatures. This is also with an AMD (Phenom II) processor.

[frign]

Less heat, but more energy consumption

My observations as well. Anything other than the powersave governor makes my HTPC fry itself once it tries to do more or less anything that is remotely demanding (due to fairly low air flow capability). With powersave, it never reaches dangerous temperatures. This is also with an AMD (Phenom II) processor.

The computer runs with less Watts over a longer period of time. In effect, it runs cooler, but computation needs more energy overall.
Just tell me if you want me to give you an example.

[GreatEmerald]

The computer runs with less Watts over a longer period of time. In effect, it runs cooler, but computation needs more energy overall.

Thankfully, an HTPC never really needs to do anything extraordinarily complex with computations.

[Ericg]

The computer runs with less Watts over a longer period of time. In effect, it runs cooler, but computation needs more energy overall.
Just tell me if you want me to give you an example.

We're aware that it uses more frign, but for some bizarre reason linux seems to be worse at thermal management than windows (I dont know how thats possible... im just speaking from experience.)

For example. This very laptop (Dell XPS 13z) running Arch linux, if I place it on my lap in such a way that my leg blocks the vent the laptop will gradually rise in temperature until it hits 95C and then BIOS kills the power to the entire laptop to prevent damage.

The same laptop running Windows 7 doing the same thing, also with my leg blocking the vent, will hit 85C and stay there, never shutting down.

^While anecdotal evidence, this isnt a "This happened once, so im telling the story." I had Arch Linux on this laptop for about 8 months or so and would accidentally overheat it at least once a week. I've had Win7 on this thing for about a month now and havent accidentally overheated it even once.

If I ever put arch linux back on this laptop I very well may stick to the powersave governor just to make sure I dont accidentally damage the internals from thermal output

[Sonadow]

We're aware that it uses more frign, but for some bizarre reason linux seems to be worse at thermal management than windows (I dont know how thats possible... im just speaking from experience.)

It's open knowledge that Linux is inferior to Windows where thermal management is concerned. Generally, as long as one is using the open drivers heat is always going to be an issue.

Once again, it's personal experience, but running my AMD notebook off the open drivers always had the graphics card and the processor idling at a very high 62 - 65 C, even with the powersave governor activated since 2009 till today. Compiling software or running Netbeans can see the temps climb to near critical levels of 80+ C and the notebook subsequently kills itself to protect the internals. This never happened under Windows.

When Catalyst was installed back then the temps can drop to as low as 57 - 59C. Unfortunately, my card is no longer supported by Catalyst so my laptop today doubles up as both a notebook and a crotch warmer / hand warmer.

[frign]

Sadly a common problem

We're aware that it uses more frign, but for some bizarre reason linux seems to be worse at thermal management than windows (I dont know how thats possible... im just speaking from experience.)

For example. This very laptop (Dell XPS 13z) running Arch linux, if I place it on my lap in such a way that my leg blocks the vent the laptop will gradually rise in temperature until it hits 95C and then BIOS kills the power to the entire laptop to prevent damage.

The same laptop running Windows 7 doing the same thing, also with my leg blocking the vent, will hit 85C and stay there, never shutting down.

^While anecdotal evidence, this isnt a "This happened once, so im telling the story." I had Arch Linux on this laptop for about 8 months or so and would accidentally overheat it at least once a week. I've had Win7 on this thing for about a month now and havent accidentally overheated it even once.

If I ever put arch linux back on this laptop I very well may stick to the powersave governor just to make sure I dont accidentally damage the internals from thermal output

Ok, good to know that. Most applets show up the "powersave" governor and most normal users think it actually saves power.

Laptops are an unique case when it comes to Linux: I for example have a small Apple Desktop computer and actually had to write my own fan-control software, because the Kernel was just doing such a bad job with it.
I would recommend everybody to do the same to keep the temperature low enough. But still, my computer idles at 42?C, which is a lot for my purposes.

[GreatEmerald]

Laptops are an unique case when it comes to Linux: I for example have a small Apple Desktop computer and actually had to write my own fan-control software, because the Kernel was just doing such a bad job with it.
I would recommend everybody to do the same to keep the temperature low enough. But still, my computer idles at 42?C, which is a lot for my purposes.

Well of course I'm running lm_sensors with fancontrol. It's still not all that helpful, though. The fact that the sensor data of the HTPC CPU is blacklisted from lm_sensors isn't helping, either (although there are motherboard CPU sensors - just that they can't track each core and are not as close to the CPU).