CPU Performance & Efficiency: SPEC2006

We move on with our analysis by using SPEC2006 on the Snapdragon 855 QRD. SPEC2006 is an important benchmark as not only does it represent a tool that is used by many companies to architect their CPU designs, but it also a very well understood and academically documented workloads that can serve as a macro-benchmark to determine microarchitectural aspects of a CPU and system.

It’s to be noted that SPEC2006 has been deprecated in favour of SPEC2017, and although we’ll switch to that at some point, for mobile platforms SPEC2006 still represents a good benchmark. Because our scores aren’t official submissions, as per SPEC guidelines we have to declare them as internal estimates from our part.

A Big Note on Power on the QRD

Although for this article I was able to collect power figures for both CPU and GPU workloads, the figures are not of an as high certitude as when measured on commercial devices. The reason for this is that much like last year’s Snapdragon 845 QRD, this year’s 855 platform reports rather high idle power in the 950-1050mW range, about 500mW more than one would expect in a final product. Because our power measurement methodology represents publishing active system power, meaning we measure total power during a given workload and subtract the idle power under the same conditions, there is a degree of uncertainty if the idle power by default is quite high.

Today’s power efficiency figures thus merely represent a guideline – and we’ll make sure to re-test the results once we get our hands on final commercial devices.

The Results – The Snapdragon 855 Performs Admirably

We’ll start off with the aggregate results and drill down in the detailed results later:

The Snapdragon 855 ends up performing extremely well, ending up neck-and-neck with the Kirin 980’s performance, which shouldn’t come as too big of a surprise.

In SPECint2006, the Snapdragon 855 performs 51% better than the Snapdragon 845, all while improving power efficiency by 39% over its predecessor. Against the Kirin 980 which is currently its nearest Android competitor, the Snapdragon just slightly edges ahead by 4%.

In SPECfp2006, the Snapdragon 855 shows an even bigger 61% leap over the Snapdragon 845, and also manages to better showcase the 9% clock speed advantage over the Kirin 980, sporting a similar performance lead.

Again what is most important in these results is the power efficiency figures. One of the things that had me worried during Qualcomm’s Snapdragon 855 launch in Hawaii last month is that the company pretty much avoided talking or publishing any meaningful power efficiency claims on the side of the CPU. Fortunately it seems there wasn’t any need to be concerned as the Snapdragon 855, at first glance, seems to be extremely efficient even on the high clocked 2.85GHz Prime core.

Detailed Results

Drilling down into the detailed results, the one comparison that is most interesting is the performance of the Snapdragon 855 against the Kirin 980. On one hand the Snapdragon 855 is clocked 9% higher as well as promises some tuned microarchitectural characteristics which promise to improve IPC – while on the other hand HiSilicon’s implementation is more straightforward and brings with itself a bigger L3 cache as well as memory latency advantages.

In the vast majority of workloads, both chipsets are neck-and-neck, only diverging in some key aspects. In less memory hierarchy demanding workloads, the Snapdragon more easily is able to showcase its clock speed advantage. In more latency sensitive workloads, this difference shrinks or reverses. 462.libquantum is an interesting result as Qualcomm commented that its lead here is primarily due to the customisations made on the CPU core – although they wouldn’t exactly specify which aspect in particular is bringing the boost.

The biggest performance discrepancy on the negative side of things is the 13% disadvantage in 458.sjeng – the benchmark is most sensitive to branch mispredictions and again here Qualcomm has stated they’ve made changes to the branch data structures of the core.

What is most odd for me to see as a result, is the fact that 429.mcf performs admirably well on the Snapdragon 855 – which goes against intuition given the platform’s memory latency disadvantage. It is possible here that the Snapdragon 855 performs better than the Kirin 980 due to its better L3 cache latency?

On the SPECfp2006 results, the results can be very clearly categorised into two sets: In one set the Snapdragon 855 clearly showcases a healthy advantage over the Kirin 980, up to very notable 17% and 22% leads in 447.dealII and 453.povray. In the other set, the Snapdragon is again neck-and-neck with the Kirin 980, and these happen to again be the workloads that are most memory sensitive in the FP suite.

Overall, the Snapdragon 855’s CPU performance does not disappoint. Performance on average is ahead of the Kirin 980, although not by much. Here both chipsets are most of the time neck-and-neck, and it will mostly depend on the workload which of the two will take the lead.

More important than performance, the efficiency of the Snapdragon 855 is top-notch, exceeding what I had expected from the higher clock implementation of the chip. There is still a degree of uncertainty over the power numbers on the QRD platform, but if these figures are representative of commercial devices, then 2019’s flagship will see excellent battery life.

Introduction & Specifications Inference Performance: Good, But Missing Tensor APIs
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  • Spunjji - Wednesday, January 16, 2019 - link

    Sorry, but that's just not true. I have yet to use a phone that feels consistently faster than the OnePlus 6 I'm currently using as a daily driver, and I've done a whole bunch of messing with custom ROMs / kernels, starting back with Cyanogenmod 6 on a Dell Streak.
  • gijames1225 - Tuesday, January 15, 2019 - link

    Sounds very positive given that phones already perform great at the flagship level. The single core improvement is greatly welcomed given how much that matters for javascript.
  • fred666 - Tuesday, January 15, 2019 - link

    I like their performance over time graph on page 1.
    It shows the 855 to be faster than the 845, which is faster than the 835, which is slower than the 820. What? Their performance dropped in that generation?
  • yeeeeman - Wednesday, January 16, 2019 - link

    Yes. In floating point, the SD820 based on their own custom cores (built on an evolution of Krait cores called Kryo) was much better than everything, including next gen SD835 which used an IP from ARM the cortex A72.
  • fred666 - Wednesday, January 16, 2019 - link

    so it pretty much means their graph is worthless. Floating point should not be the primary indicator of performance, integers are much more used by most popular use cases
  • Spunjji - Wednesday, January 16, 2019 - link

    He didn't say the graph shows FP performance, he just mentioned that 820 was unusually strong in that area. My guess is it's a representation of overall performance based on some or other standard benchmark. That doesn't make it "worthless", because it's literally only there to show a rough comparison between historical chipsets.
  • cpkennit83 - Thursday, January 17, 2019 - link

    Actually it was the A73. The A72 is actually stronger in fp but slower in integer workloads
  • stennan - Tuesday, January 15, 2019 - link

    Please do a podcast soon. There has been so much going on with pc Cpu/gpu and now incoming mobile cpu that I miss having the anandtech deep dive!
  • melgross - Tuesday, January 15, 2019 - link

    Well, it’s all very interesting, but still the elephant in the room is Apple’s A series, no matter what. Take that out, and the 855 and 980 are excellent chips, but with it in, they are just mediocre.
  • cpkennit83 - Tuesday, January 15, 2019 - link

    They are excellent chips no matter what. A12 big cores are twice as large or more than a76 cores.
    No android Oem is willing to pay a big premium for their flagship socs, so the qualcomms and huaweis of the world don't pressure arm to spend the big $$ needed to fund the development of truly wide cores. The only one who seems interested in going big is Samsung, but they can't get their act together.

    Still performance is more than adecuate in the a76 flagship SOCS, and efficiency is slightly better than a12, so for me this generation is the best in the android space since the SD800.

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