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Samsung Galaxy S4 Slows Down Under Heavy Load in 4.4

By - Source: Tom's Hardware US | B 18 comments

Samsung's Android 4.4 update for the Galaxy S4 introduces aggressive CPU throttling.

As PC enthusiasts, we're no strangers to situations arising where performance gets dinged over time. Most recently, we identified the Radeon R9 290X's bad habit of heating up and shedding clock rate during heavy 3D loads, prompting AMD to introduce a new driver that pushed fan speeds higher to keep up with cooling. That's not as easy of a behavior to address in the mobile space, though. Devices aren't cooled actively, so balancing performance, thermals, and battery life becomes a delicate matter of industrial design, materials, and carefully-defined profiles.

Generally, operating systems become more resource-taxing as features pile up. But Google preached numerous efficiency gains in moving to Android 4.4 KitKat. We recently applied Samsung's update to our Galaxy S4 and discovered some interesting performance behaviors that weren't a part of previous builds.

In short, Samsung's stock 4.4 ROM for the Galaxy S4 employs an exceptionally aggressive dynamic voltage and frequency scaling (DVFS) algorithm. Compared to previous versions of Samsung's ROM, we've found that in 4.4 it takes far less load/heat to reach the threshold at which the SoC starts throttling back. At its worst, you'll see CPU complex frequencies of 918 MHz, which is less than half of the Snapdragon 600's 1.9 GHz ceiling.

Our main points of comparison are between 4.4 and 4.2, as 4.3 is tainted with specially-programmed behavior when the ROM detected the presence of a named benchmark and force the phone to run the Snapdragon 600's clock rate up to 1.9 GHz and hold it there when it detected a specified APK, such as 3DMark, so long as the SoC's temperature remained somewhere under a Qualcomm-defined Tj temperature. The Galaxy Note 3 was also guilty of this under Android 4.3.

We ran a bevy of benchmarks and consistently found that the Galaxy S4's CPU complex (and presumably GPU as well) would throttle so aggressively that performance results tanked after just a couple of iterations. Running the exact same tests within the same time window under room temperatures on 4.2 did not exhibit nearly anywhere near the same degree of throttling. We confirmed our findings in other benchmarks as well.

This sort of behavior isn't limited to benchmarks, unfortunately. We fired up EA's Real Racing 3 and watched the frequency drop from 1890 MHz, down several steps, before settling at 918 MHz. As the CPU complex throttles down, we have evidence to suggest that the GPU scales back as well in defined steps.

With no changes to the hardware design or thermal setup, the clear culprit is Samsung's DVFS algorithm. Mind you, both 4.2 and 4.3 employed DVFS as well, but Samsung clearly altered the implementation in 4.4 to affect the throttle points. It's not clear if this has anything to do with LucidLogix's GameXtend technology; the company wouldn't comment when we asked for feedback. Nor do we have data to reflect real-world battery life gains garnered from a quicker-to-spin-down version of the S4.

But the community at XDA-Developers already came up with a hack to disable Samsung's DVFS, essentially unshackling the Snapdragon 600 to perform more aggressively. This does not force the SoC to run at full-tilt, as it does under its application-detected Android 4.3 ROM. Rather, it raises the thermal limit to what's still believed to be within engineered guidelines. It's important to note that installing any sort of modification will void your warranty and lead to risks of bricking your phone. It's also going to burn through power more quickly, as higher clock rates and added heat work against efficiency.

When purely looking at performance from a "first run from cold" perspective, 4.4 delivers mostly the same as 4.2. Aside from gaming, most phone use is in short, sporadic bursts, allowing the SoC to drop back to idle.

This new behavior from Samsung's 4.4 ROM is disappointing for those wanting maximum performance from their SoC, especially given that the new DVFS system actually results in something far less consistent than the two major software versions before it.

A positive side effect of such conservative SoC behavior is its effect on power consumption and heat; lower voltages and frequencies generally result in less of both. Samsung could possibly be accounting for the fact that the first S4s off the line are now a year old with declining battery capacity, and this software tweak will preserve the company's original battery claims. That said, Samsung designs its phones with removable batteries, making it a cinch to replace. Having a phone that now slows down under heavy load could lead to conspiracy theories now that there's the newer, faster Galaxy S5 heading to stores worldwide.

Special thanks to Zackariah Khazraeinazmpour and Jon Carroll for their help in running benchmarks on their phones to help us characterize performance.

Follow Marcus Yam @MarcusYamFollow us @tomshardware, on Facebook and on Google+.

Add your comment Display 19 Comments.
  • 0 Hide
    mauller07 , April 1, 2014 12:16 PM
    They need to start releasing phones with Sailfish O/s, bloody good looking operating system with support for QT c++ programming for native software while also being able to use Android apps using Alien Dalvik.Incredibly fast, lightweight and solid operating system, will actually make use of all this hardware instead of it being required just to run bloody android itself.
  • -1 Hide
    abimocorde , April 1, 2014 12:42 PM
    Thank God i think i only use heavy 3D loads 5 minutes a day.
  • 1 Hide
    Shaggy Bug , April 1, 2014 1:02 PM
    Why is it that it takes samsung 4 months so far to release 4.4 for android but company's like htc Sony and lg have several phones running smoothly on 4.4 while samsung Is down with 2 they need to get it together
  • -2 Hide
    abimocorde , April 1, 2014 1:45 PM
    Quote:
    Spamsung products revealed for the third rate shit they are.

    Quite happy with my Samsung devices. Maybe your problem is the user, not the hardware.

  • 0 Hide
    mynith , April 1, 2014 2:31 PM
    I never knew the Galaxy S4 had a Snapdragon inside. I always thought it was one of Samsung's own Exynos series chips.
  • 3 Hide
    leandrolnh , April 1, 2014 2:51 PM
    Quote:
    I never knew the Galaxy S4 had a Snapdragon inside. I always thought it was one of Samsung's own Exynos series chips.
    There are two versions of GS4: the I9500 with the octa-core Exynos (3G only) and the I9505 with the Snapdragon 600 and LTE.
  • 0 Hide
    rohitbaran , April 1, 2014 3:29 PM
    Why no nexus 5 in any of the graphs?
  • 0 Hide
    Marcus Yam , April 1, 2014 3:30 PM
    Quote:
    Why no nexus 5 in any of the graphs?
    Nexus 5 runs the Snapdragon 800.
  • -1 Hide
    therealduckofdeath , April 1, 2014 5:41 PM
    Quote:
    The 4yo iPhone 4 handles iOS7.1 just fine. Obviously it's not as fast as the 5s but I've used it and its pretty smooth. The 10 month old S4 can't run the latest Android OS? How pathetic is that?
    The GS4 is the most stable smartphone on the market. The iPhone you referred to is the buggiest "high-end" phone anyone has bought in a long time.

    http://www.androidcentral.com/apps-crashed-most-gingerbread-things-have-improved-according-report

    Nice try, though.
  • 2 Hide
    flaxx , April 1, 2014 8:39 PM
    Quote:
    Quote:
    The 4yo iPhone 4 handles iOS7.1 just fine. Obviously it's not as fast as the 5s but I've used it and its pretty smooth. The 10 month old S4 can't run the latest Android OS? How pathetic is that?
    The GS4 is the most stable smartphone on the market. The iPhone you referred to is the buggiest "high-end" phone anyone has bought in a long time.http://www.androidcentral.com/apps-crashed-most-gingerbread-things-have-improved-according-reportNice try, though.
    Talk about a gross exaggeration. A 0.5% lower crash rate is so insignificant that a user would never even notice it. Furthermore, these are statistics from applications, not the OS, and I'm willing to bet it's due to lame Java programmers that know nothing about proper memory management. That's all fine in general applications (since Objective C has ARC), but when you develop games in OpenGS, that gets flushed out as you're using C on iOS. As as the article you referenced reads, "graphically-intensive games naturally crashed the most, while e-commerce apps crashed the least." You can have your outdated, abandoned phone. I'll take an iPhone any day of the week.
  • 0 Hide
    solarfinder , April 2, 2014 12:25 AM
    I have experience perceived behavior like that of what you have reported. I live my phone, however, like with any device, heat kills. I'm running a custom rom with new management and my performance is maintained at my peril. Nice write up.
  • -3 Hide
    therealduckofdeath , April 2, 2014 4:36 AM
    Quote:
    Quote:
    Quote:
    The 4yo iPhone 4 handles iOS7.1 just fine. Obviously it's not as fast as the 5s but I've used it and its pretty smooth. The 10 month old S4 can't run the latest Android OS? How pathetic is that?
    The GS4 is the most stable smartphone on the market. The iPhone you referred to is the buggiest "high-end" phone anyone has bought in a long time.http://www.androidcentral.com/apps-crashed-most-gingerbread-things-have-improved-according-reportNice try, though.
    Talk about a gross exaggeration. A 0.5% lower crash rate is so insignificant that a user would never even notice it. Furthermore, these are statistics from applications, not the OS, and I'm willing to bet it's due to lame Java programmers that know nothing about proper memory management. That's all fine in general applications (since Objective C has ARC), but when you develop games in OpenGS, that gets flushed out as you're using C on iOS. As as the article you referenced reads, "graphically-intensive games naturally crashed the most, while e-commerce apps crashed the least." You can have your outdated, abandoned phone. I'll take an iPhone any day of the week.


    Haha!... Now it's all gross exaggerations, because the iPhone is the buggy one? Cry me a river. Seems like you're used to it, considering how often your apps crashes... :) 

    You're correcting your own faulty assumptions while you're typing... What do you expect me to respond? "Yes, we know it's sad. Apple trolls has been lying through their teeth all these years". But we both already knew that, too, didn't we?
  • -1 Hide
    stratplaya , April 2, 2014 6:00 AM
    They'll probably tweak this in version 4.5 Snickers.
  • 0 Hide
    Ninjawithagun , April 2, 2014 9:46 AM
    FIrst off, just because a phone's processor runs at it's maximum capability doesn't mean it's cheating. The Galaxy S4 is able to perform within the hardware specifications of it's design and in doing so can beat other comparable phones on the market. So, how is this cheating? If Samsung had modified the operating system to somehow exploit the benchmarks directly and push out inflated performance that was not real, then I could see it being called cheating. But, this is not the case here. So, all-in-all the Galaxy S4 is a superior product that is now handicapped by the new Kit Kat OS for no reason at all. Absolutely the most stupid thing I've ever heard. Add this debacle to the problem Kit Kat introduces with the restricted use of external storage and what you have a once great Google turning to absolute crap fast!
  • 0 Hide
    AGP123 , April 2, 2014 1:29 PM
    The reason for this decrease in performance is indeed Samsung's retarded DVFS system. It can be fixed with no consequences using this mod, but it requires root, and you will void your warranty.http://forum.xda-developers.com/showthread.php?t=2674928
  • 0 Hide
    SamR0ck , April 2, 2014 2:06 PM
    People should start exploring alternative called "Windows Phone 8". Super stable, well designed and very efficient.
  • -3 Hide
    therealduckofdeath , April 2, 2014 2:08 PM
    Quote:
    People should start exploring alternative called "Windows Phone 8". Super stable, well designed and very efficient.
    LOL... Oh, you were serious?
  • 0 Hide
    Minerva , April 4, 2014 1:34 AM
    Hey guys, in the screenshot of RealRacing3, what app are you using to display the clockspeed?
  • 0 Hide
    AGP123 , April 19, 2014 1:29 PM
    Seriously, more people need to know about this. Just before the new model releases, Samsung cripples performance of the old model. They're completely ruthless, market domination at all costs.
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