CPU and System Performance

Snapdragon 820 included Qualcomm’s first fully-custom 64-bit CPU cores. The unique microarchitecture’s floating-point IPC was very good, but integer IPC was no better than ARM’s older A57 core. Its power efficiency was lower than competing cores as well. Instead of using a revised quad-core Kryo arrangement for Snapdragon 835, Qualcomm decided to go in a completely different direction.

The new Kryo 280, despite the similar name, shares no design DNA with the original Kryo. Its an octa-core, big.LITTLE configuration with four “performance” cores and four lower-power “efficiency” cores. What makes Kryo 280 unique, however, is that it’s the first design to use ARM’s new "Built on ARM Cortex Technology" (BoC) license, which allows vendors to customize ARM cores. This new semi-custom option gives vendors the ability to differentiate their products from those using ARM’s stock cores while avoiding the more costly route of creating a fully-custom design from scratch.

The BoC license allows the vendor to request certain modifications, particularly to the fetch block and issue queues, but certain parts of the microarchitecture are off limits, including the decoder and execution pipelines, because modifying these blocks requires too much effort. Qualcomm is not disclosing which ARM cores serve as the foundation for Kryo 280 or precisely which modifications it requested, but it did say that both CPU clusters use semi-custom cores. Qualcomm also confirmed that Snapdragon 835’s memory controllers are its own design.

Geekbench 4 - Integer Performance
Single Threaded
  Snapdragon 835 Snapdragon 821
(% Advantage)
Snapdragon 810
(% Advantage)
AES 905.40 MB/s 559.10 MB/s
(61.9%)
714.47 MB/s
(26.7%)
LZMA 3.13 MB/s 2.20 MB/s
(42.3%)
1.92 MB/s
(63.0%)
JPEG 16.80 Mpixels/s 21.60 Mpixels/s
(-22.2%)
12.27 Mpixels/s
(36.9%)
Canny 23.60 Mpixels/s 30.27 Mpixels/s
(-22.0%)
23.63 Mpixels/s
(-0.1%)
Lua 1.84 MB/s 1.47 MB/s
(25.2%)
1.20 MB/s
(53.3%)
Dijkstra 1.73 MTE/s 1.39 MTE/s
(24.5%)
0.91 MTE/s
(90.1%)
SQLite 53.00 Krows/s 36.67 Krows/s
(44.5%)
33.30 Krows/s
(59.2%)
HTML5 Parse 8.67 MB/s 7.61 MB/s
(13.9%)
6.38 MB/s
(35.9%)
HTML5 DOM 2.26 Melems/s 0.37 Melems/s
(510.8%)
1.26 Melems/s
(79.4%)
Histogram Equalization 52.90 Mpixels/s 51.17 Mpixels/s
(3.4%)
53.60 Mpixels/s
(-1.3%)
PDF Rendering 50.90 Mpixels/s 52.97 Mpixels/s
(-3.9%)
43.70 Mpixels/s
(16.5%)
LLVM 196.80 functions/s 113.53 functions/s
(73.3%)
108.87 functions/s
(80.8%)
Camera 5.71 images/s 7.19 images/s
(-20.6%)
4.69 images/s
(21.7%)

The Snapdragon 835’s Kryo 280 CPU shows a noticeable improvement in integer IPC relative to the 820/821’s Kryo core. This is not unexpected, however, considering integer performance was not one of Kryo’s strengths. While most workloads see large increases, there are a few regressions too, notably in JPEG, Canny, and Camera. We saw this same performance pattern from Kirin 960’s A73 CPU as well. These integer results, along with L1/L2 cache behavior, match the A73’s unique performance fingerprint, confirming that Kryo 280’s performance cores are based on ARM’s latest IP.

Quickly comparing Snapdragon 835 and Kirin 960 Geekbench 4 Integer results also shows performance variations that cannot be fully explained by differences in frequency or normal testing variance. The differences only occur in a few specific tests and range from 9% to -5%, which again is not completely unexpected given the limited number of modifications the BoC license allows for semi-custom designs.

Geekbench 4 (Single Threaded) Integer Score/MHz

The chart above divides the overall integer score by CPU frequency, making it easier to directly compare IPC. Taken as a whole, the performance of Kryo 280’s semi-custom performance core is not much different than the Kirin 960’s A73 core in this group of workloads, with individual gains and losses nearly averaging out. Its overall IPC is also only about 6% higher than A72 and 14% higher than A57. Its advantage over Snapdragon 820/821 widens to 22%, partly because Kryo’s poor performance in the LLVM and HTML5 DOM workloads drags down its overall score.

While Snapdragon 835 leads other SoCs by a slim margin in this test, it’s not a sweeping victory. Just like we saw with Kirin 960’s A73 cores, performance improves in some workloads but regresses in others.

Geekbench 4 - Floating Point Performance
Single Threaded
  Snapdragon 835 Snapdragon 821
(% Advantage)
Snapdragon 810
(% Advantage)
SGEMM 11.5 GFLOPS 12.2 GFLOPS
(-5.7%)
11.0 GFLOPS
(4.2%)
SFFT 2.9 GFLOPS 3.2 GFLOPS
(-9.7%)
2.3 GFLOPS
(25.2%)
N-Body Physics 879.6 Kpairs/s 1156.7 Kpairs/s
(-24.0%)
580.2 Kpairs/s
(51.6%)
Rigid Body Physics 6181.7 FPS 7171.3 FPS
(-13.8%)
4183.4 FPS
(47.8%)
Ray Tracing 232.6 Kpixels/s 298.7 Kpixels/s
(-22.0%)
130.1 Kpixels/s
(78.7%)
HDR 7.8 Mpixels/s 10.8 Mpixels/s
(-27.6%)
6.4 Mpixels/s
(21.9%)
Gaussian Blur 23.4 Mpixels/s 48.5 Mpixels/s
(-51.8%)
21.9 Mpixels/s
(6.7%)
Speech Recognition 13.9 Words/s 10.9 Words/s
(27.5%)
8.1 Words/s
(71.4%)
Face Detection 513.8 Ksubs/s 685.0 Ksubs/s
(-25.0%)
404.4 Ksubs/s
(27.0%)

Snapdragon 835’s Kryo 280 takes two steps backwards when running Geekbench 4’s floating-point workloads, finishing well behind Snapdragon 820/821’s Kryo core and even a little behind SoCs using the A72 core. Its IPC is on par with the Kirin 960’s A73 core, with even less variation between individual scores than we saw when running the integer workloads.

The A73’s slight performance regression relative to the A72, which also applies to the semi-custom Kryo 280, is a bit surprising, because their NEON execution units are relatively unchanged from the A72’s design. If anything, the A73’s lower-latency front end and improvements to its fetch block and memory system should give it an advantage, but that’s not the case. The A73’s narrower decode stage could limit performance for some workloads but not all. Both the Kirin 960’s A73 and Snapdragon 835’s Kryo 280 show reduced L2 cache read/write bandwidth (and lower L1 write bandwidth) relative to A72, which could also negatively impact performance.

Geekbench 4 (Single Threaded) Floating Point Score/MHz

Snapdragon 835’s floating-point IPC is 23% lower than Snapdragon 820/821’s. One has to wonder if this is the result of a forced compromise or a willing change in design philosophy. When Qualcomm started work on Kryo more than 2 years ago, it may have envisioned new workloads that never materialized. Or it could be that with more compute workloads shifting to the GPU and DSP to improve efficiency, it was willing to sacrifice some floating-point performance to save area and power.

Geekbench 4 - Memory Performance
Single Threaded
  Snapdragon 835 Snapdragon 821
(% Advantage)
Snapdragon 810
(% Advantage)
Memory Copy 4.70 GB/s 7.82 GB/s
(-39.9%)
3.99 GB/s
(17.8%)
Memory Latency 13.95 Mops/s 6.64 Mops/s
(110.1%)
4.29 Mops/s
(225.2%)
Memory Bandwidth 17.95 GB/s 13.53 GB/s
(32.7%)
7.15 GB/s
(151.0%)

The Kryo 280, A73, A72, and A57 cores all have 2 address generation units (AGUs). Unlike the A72/A57, however, which use dedicated AGUs for load and store operations, each AGU in Kryo 280/A73 is capable of performing both operations. For Kirin 960, this change, among others, reduces memory latency and significantly improves bandwidth to main system memory relative to Kirin 950.

Snapdragon 835’s memory latency and bandwidth numbers are even better than Kirin 960’s—up to 11% after accounting for differences in CPU frequency. The 835 sees impressive gains over the 820/821 too. Switching to Kryo 280 does not provide the same bandwidth boost as the switch to A73 did for Kirin 960, however, because Kryo’s 2 AGUs were already capable of performing both load and store operations, albeit with a higher latency in some cases.

System Performance

So far our initial results show Snapdragon 835’s Kryo 280 is a big.LITTLE combination of semi-custom A53 and A73 CPU cores, whose integer and floating-point IPC is similar to Kirin 960. System-level tests like PCMark, which includes several realistic workloads that stress the CPU, GPU, RAM, and NAND storage using standard Android API calls, are affected by more than just CPU IPC and memory latency, however. Device OEMs tune the software parameters that control the scheduler and DVFS systems to achieve the desired balance between performance and battery life, to meet quality of service goals, and to stay within a particular design's thermal limits.

No doubt we'll see performance vary among the upcoming Snapdragon 835 devices, just like we do with other SoCs, but for now we see Qualcomm’s 835 MDP/S with the top overall score in PCMark, just barely ahead of the Mate 9 and its Kirin 960 SoC. It’s also 23% faster overall than the top-performing Snapdragon 821 phone.

PCMark - Work 2.0 Performance Overall

PCMark - Web Browsing 2.0

PCMark - Writing 2.0

PCMark - Data Manipulation 2.0

The Snapdragon 835 MDP/S performs well in the Web test, although its advantage over the Mate 9 is only 10%. Its performance lead over the Snapdragon 820/821 phones, which all fall behind SoCs using ARM’s A72 and A73 CPUs, grows to 34% in this integer-heavy test.

The PCMark Writing test generates frequent, short bursts of activity on the big CPU cores while performing a variety of operations, including PDF processing and file encryption (both integer workloads), memory operations, and even reading and writing some files to internal NAND. Because of this, it tends to produce the most varied results. Take the spread between the Snapdragon 820/821 phones, for example, where the LeEco Le Pro3 is 40% faster than the Galaxy S7 edge. The performance difference between the Snapdragon 835 MDP/S and Mate 9 is negligible, however. Comparing Snapdragon 835 to older members of the Snapdragon family reveals more significant differences; it’s 24% faster than the LeEco Le Pro3 (S821), 80% faster than the Nexus 6P (S810), and 162% faster than the Lenovo ZUK Z1 (S801AC).

The PCMark Data Manipulation test is another primarily integer workload that measures how long it takes to parse chunks of data from several different file types and then records the frame rate while interacting with dynamic charts. Once again the Snapdragon 835 MDP/S and Mate 9 deliver similar performance, but they separate themselves a little further from the pack. Like we saw in the Writing test, the phones using Snapdragon 820 show significant performance variation, providing another example of how OEM tinkering impacts the user experience. The Snapdragon 835 MDP/S outperforms the Pixel XL by 28% and the LG G5 by 111%.

PCMark - Video Editing 2.0

PCMark - Photo Editing 2.0

The Video Editing test, which uses OpenGL ES 2.0 fragment shaders for applying video effects, actually presents a very light load to the system. After monitoring the behavior of several phones while running this test, I’ve noticed that GPU frequency remains close to idle and most phones do not migrate threads to the big CPU cluster, using the little A53 cluster exclusively, which is why we see very little performance variation in this test.

The Photo Editing test applies a number of different photo effects and filters with both the CPU and GPU. The Snapdragon 835 MDP/S and the phones using Snapdragon 820/821 rise to the top of the chart thanks to their Adreno GPU’s strong ALU performance. The 835’s Adreno 540 GPU helps it perform 33% better than the highest performing phone with an ARM GPU, the Mate 9 and its Mali-G71.

Kraken 1.1 (Chrome/Safari/IE)

WebXPRT 2015 (Chrome/Safari/IE)

JetStream 1.1 (Chrome/Safari)

Yes, the iPhones perform well in these JavaScript tests. No, you cannot use these tests to compare IPC between Apple’s A-series SoCs and those found in Android phones, because they are running different browsers. A significant portion of the iPhones’ performance advantage actually comes from Safari’s JavaScript engine.

The Snapdragon 835 MDP/S compares favorably to other phones using the Chrome browser (all of the phones are using the latest version). It joins the Snapdragon 820/821 phones at the top of the chart in Kraken, although, its performance is no different. It essentially matches the Mate 9 in JetStream too, but pulls ahead of the Snapdragon 820/821 phones by 15% to 37%. Performance is unexpectedly good in WebXPRT 2015 where it pulls ahead of the Mate 9 by 24% and up to 67% over the Galaxy S7 (S820).

As an additional point of interest, and to further highlight the software layer’s effects, we also ran these tests using Qualcomm’s internally developed browser that’s optimized for Snapdragon SoCs. Kraken only sees a modest improvement to 2,305 ms, but JetStream improves by 24% to 87 and WebXPRT 2015 jumps to 280, an 82% improvement.

Introduction GPU Performance
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  • yankeeDDL - Wednesday, March 22, 2017 - link

    In most of the graphs where the iPhone is present, they trounce anything else. It is quite disappointing, being an Android enthusiast, to see that the 835 does not catch up with a 6 month old phone... Reply
  • shing3232 - Wednesday, March 22, 2017 - link

    but the bright side is that huge reduction in Power usage compare to 820 Reply
  • ddriver - Wednesday, March 22, 2017 - link

    This is comparing apples to oranges. Unless the two CPUs run the same code, performance is irrelevant.

    The web is majorly a shitpile of bloat, ridden with inefficiency. Apple simply invested more time into optimizing their web / JS implementation. This is not really indicative of CPU performance, only of web implementation optimizations.

    And while it is true that apple's single threaded performance has been better, that is only a part of the story. You have the budget of n amount of transistors to put into x amount of total performance. If you have more threads, then obviously individual threads will be slower. Optimizing for low count threads is actually a pretty good idea given the typical mobile device usage patterns.

    Why do most ARM chipmakers push for higher core count is a mystery to me. That is a STUPID strategy. It makes it that much harder to squeeze the most of your hardware.

    I've been running proprietary software on phones and tables since 2012, software designed to scale adequately, and as a result, I see better overall performance from flagship android devices despite apple's better ST performance, but only because of the kind of workloads I am running. So while the chips aren't anywhere nearly as slow as AT's lame benchmarking suite would suggest, it is not exactly straightforward to get the max of their performance.

    Lastly, the is this thing called "fast enough". Even if apple chips are traditionally faster in typical mobile applications than those found in android devices, this is not really an issue if the slower devices are still fast enough. I haven't really seen bottlenecks in the few 3rd party android apps I am using, so even with software that has not been designed to make use of many cores, things still run fast enough to not present an issue in regards with user experience.

    All in all, in general I'd say ARM is not really trying to make things good, at least not as far as the user is concerned. The only reason apple invest into tangibly improving on the stock ARM designs is for the hype factor, rather than actually putting that performance into productivity. Mobile platforms are doubly limited just to make sure they don't revolutionize computing, both in terms of hardware, and available software. Pretty much next to useless toys, intended to use you far more than you use them, unless you have the resources to put into developing proprietary software tailored to your productivity needs.
    Reply
  • close - Thursday, March 23, 2017 - link

    Apple has yet another advantage. Since it controls its ecosystem end to end it can optimize the software for their specific hardware. In the Android ecosystem you have configurations ranging from 1 to 10 cores (or more?), so many different generations, so many different custom and semi-custom cores. A little trickier to optimize. So Android OEMs go for the numbers. Core numbers that is. Now with 25% more cores.

    And lets not forget another aspect. Historically Apple focused on optimizing the SoC layout for performance which led to much bigger cores which doesn't seem to be the method of choice in the Android ecosystem. They worked on improving the density, especially with the A8 and the A10.
    Reply
  • ericgl21 - Wednesday, March 22, 2017 - link

    Yep...iPhone's A10 Fusion chip is very capable indeed. And in September they're probably going to announce a better one (maybe called "A11"). Looks like Apple is ahead of everyone else, especially when it comes to web-related speeds. Reply
  • Samip - Wednesday, March 22, 2017 - link

    Did you not read the disclaimer right below the web benchmarks? Reply
  • joms_us - Wednesday, March 22, 2017 - link

    Guess what? I have never seen any comparison between iPhone 7 and flagship Android phone with SD821 where iPhone 7 is faster in app and browsing site. These benchmarks mean nothing if you are using different platforms particularly OS.

    Check out this comparison

    https://youtu.be/mcTAXsFHu5I
    Reply
  • gigathlete - Wednesday, March 22, 2017 - link

    Check out this comparison: https://www.youtube.com/watch?v=vm8zC2VAr8w Reply
  • joms_us - Wednesday, March 22, 2017 - link

    Bwaha PhoneBluff. Who launches 10 apps in a minute and close it right away with the home button? Retards?

    His finger is faster on the home button of iPhone than OP3T =D
    Reply
  • TadzioPazur - Wednesday, March 22, 2017 - link

    This "test" is broken. Instead of measuring each activity individually, the test mashes them all together and measures total time. This makes no sense whatsoever - users are interested in doing one thing at a time, so individual tests somehow reflect perceived speed of the device.

    Measuring all together is not how we use these kind of devices. Especially that a lot of those activities reflect the mass storage sequential read. So all PhoneBuff needed to have done to show his beloved device was the fastest, was to put enough application load activities and leverage faster IO.

    So I do think this "test" is so much worse than the above, posted by @joms_us.
    Reply

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