The Qualcomm Snapdragon 820 Performance Preview: Meet Kryo
by Ryan Smith & Andrei Frumusanu on December 10, 2015 11:00 AM EST- Posted in
- SoCs
- Snapdragon
- Qualcomm
- Snapdragon 820
CPU Performance: Meet Kryo
To dive right into the heart of matters then, after getting our standard benchmarks out of the way we had enough time left to load up some of our more advanced analysis tools to run on the 820 MDP/S. While Qualcomm has been somewhat forthcoming in the Kryo CPU architecture, they have never been as forward as say ARM (who is in the business of licensing the IP), so there are still some unanswered questions about what Kryo is like under the hood.
| Qualcomm CPU Core Comparison | |||||||
| Snapdragon 800 | Snapdragon 810 | Snapdragon 820 | |||||
| CPU Codename | Krait | ARM Cortex-A57 | Kryo | ||||
| ARM ISA | ARMv7-A (32-bit) | ARMv8-A (32/64-bit) | ARMv8-A (32/64-bit) | ||||
| Integer Add | 1 | 2 | 1 | ||||
| Integer Mul | 1 | 1 | 1 | ||||
| Shifter ALUs | 1 | 2 | 1 | ||||
| Addition (FP32) Latency | 3 cycles | 5 cycles | 3 cycles | ||||
| Multiplication (FP32) Latency | 6 cycles | 5 cycles | 5 cycles | ||||
| Addition (INT) Latency | 1.5 cycles | 1 cycle | 1 cycle | ||||
| Multiplication (INT) Latency | 4 cycles | 3 cycles | 4 cycles | ||||
| L1 Cache | 16KB I$ + 16KB D$ | 48KB I$ + 32KB D$ | 32KB I$ + 32KB D$? | ||||
| L3 Cache | N/A | N/A | N/A | ||||
One thing that immediately jumps out is how similar some of our results are to Krait. According to our initial tests, the number of integer and FP ALUs would appear to be unchanged. Similarly the latency for a lot of operations is similar as well. This isn’t wholly surprising as Krait was a solid architecture for Qualcomm, and there is a good chance they agreed and decided to use it as their starting point. At the same time however I do want to note that these are our initial results done rather quickly on what’s essentially a beta device; further poking later on may reveal more differences than what we’ve seen so far.
But with the above said, there’s a big difference between how many execution units a CPU design has and how well it can fill them, which is why even similar designs can have wildly different IPC. We’ll investigate this a bit more in a moment, however it’s worth noting that this is exactly the philosophy ARM has gone into with Cortex-A72, so it is neither unprecedented nor even unexpected.
Looking at the memory hierarchy and latency, our results point to a 32KB L1 data cache. For the moment I’m assuming the instruction cache is identical, as is the case on most designs, but this test is purely a data test. Meanwhile L2 cache size is a bit harder to pin down; we know that the different CPU clusters on 820 will be using different L2 cache sizes. Ultimately it's pretty much impossible to pin down the exact L2 cache size from this test alone, especially since we can't see the amount of L2 attached to the lower clocked Kryo cluster.
According to our colleague Matt Humrick over at Tom's Hardware, while investigating the matter, it seems that Qualcomm disclosed that we're looking at an 1MB L2 for the performance cluster and a 512KB L2 for the power cluster. We're still looking into independently confirming this bit of information with Qualcomm.
However what you won’t find – and much to our surprise – is an L3 cache. Our test results indicate (and Qualcomm confirms) that Snapdragon 820 does not have an L3 cache as we initially expected, with the L2 cache being the highest cache level on the chip. We initially reported there to be an L3 due to the fact that we found evidence and references to this cache block in Qualcomm's resources, but it seems the latest revision of the SoC doesn't actually employ such a piece in actual silicon, as demonstrated by the latency graph. This means that there isn’t any kind of cache back-stopping interactions between the two CPU clusters, or between the CPU and GPU. Only simple coherency, and then beyond that main memory.
| Geekbench 3 Memory Bandwidth Comparison (1 thread) | ||||||
| Stream Copy | Stream Scale | Stream Add | Stream Triad | |||
| SD 801 (2458MHz) | 7.6 GB/s | 4.6 GB/s | 4.6 GB/s | 5.2 GB/s | ||
| SD 810 (1958MHz) | 7.5 GB/s | 7.4 GB/s | 6.4 GB/s | 6.6GB/s | ||
| SD 820 (2150MHz) | 17.4 GB/s | 11.5 GB/s | 13.1 GB/s | 12.8 GB/s | ||
| SD 820 > 810 Advantage | 131% | 55% | 103% | 94% | ||
Meanwhile looking at Geekbench 3 memory performance, one can see that memory bandwidth is greatly improved over both Snapdragon 800/801 and 810. Stream copy in particular is through the roof, increasing by 131% (over double 810’s performance). Even the other tests, though not as great, are between 55% and 103%. The Snapdragon 820 also shows improved latency to main memory when compared to the Snapdragon 810, so it seems that Qualcomm made definite improvements in the memory controller and general memory architecture of the chipset, allowing the CPUs to get nearer to the theoretical total memory bandwidth offered by the memory controllers.
Moving on, let’s shift to some benchmarks that make a more comprehensive look at performance, starting with SPECint2000. Developed by the Standard Performance Evaluation Corporation, SPECint2000 is the integer component of their larger SPEC CPU2000 benchmark. Designed around the turn of the century, officially SPEC CPU2000 has been retired for PC processors, but with mobile processors roughly a decade behind their PC counterparts in performance, SPEC CPU2000 is currently a very good fit for the capabilities contemporary SoCs.
| SPECint2000 - Estimated Scores | ||||||
| Snapdragon 810 | Snapdragon 820 | % Advantage | ||||
| 164.gzip |
823
|
1176
|
43%
|
|||
| 175.vpr |
2456
|
1707
|
-30%
|
|||
| 176.gcc |
1341
|
1641
|
22%
|
|||
| 181.mcf |
789
|
593
|
-25%
|
|||
| 186.crafty |
1492
|
1449
|
-3%
|
|||
| 197.parser |
753
|
962
|
28%
|
|||
| 252.eon |
2321
|
3333
|
44%
|
|||
| 253.perlbmk |
1090
|
1384
|
27%
|
|||
| 254.gap |
1325
|
1447
|
9%
|
|||
| 255.vortex |
1043
|
1583
|
52%
|
|||
| 256.bzip2 |
867
|
1041
|
20%
|
|||
| 300.twolf |
DNC
|
DNC
|
N/A
|
|||
Even though this early preview means we don’t have the luxury of building a binary with a compiler aware of Kryo, using our A57 binaries produces some preliminary results on the 820 MDP/S. Performance does regress in a couple of places – but in other places we see performance increases by up to 52%. 820 does have a slight 10% frequency advantage over 810, so when taking into account the clock difference the IPC improvements are slightly lower. This is also showcased when comparing the Snapdragon 820 to a more similarly clocked Exynos 7420 (A57 @ 2100MHz), where the maximum advantage drops to 33% and similarly to a clock-normalized Snapdragon 810, the overall average comes in at only 5-6%. Once we get the opportunity to have more time with a Snapdragon 820 device we'll be able to verify how much the compiler settings affect the score on the Kryo architecture.
Our other set of comparison benchmarks comes from Geekbench 3. Unlike SPECint2000, Geekbench 3 is a mix of integer and floating point workloads, so it will give us a second set of eyes on the integer results along with a take on floating point improvements.
| Geekbench 3 - Integer Performance | ||||||
| Snapdragon 810 | Snapdragon 820 | % Advantage | ||||
| AES ST |
739.7 MB/s
|
700.7 MB/s
|
-5%
|
|||
| AES MT |
3.05 GB/s
|
1.99 GB/s
|
-35%
|
|||
| Twofish ST |
89.8 MB/s
|
102.7 MB/s
|
14%
|
|||
| Twofish MT |
448.5 MB/s
|
345.5 MB/s
|
-23%
|
|||
| SHA1 ST |
628.9 MB/s
|
983 MB/s
|
56%
|
|||
| SHA1 MT |
3.02 GB/s
|
2.84 GB/s
|
-6%
|
|||
| SHA2 ST |
83.5 MB/s
|
134.9 MB/s
|
61%
|
|||
| SHA2 MT |
393.4 MB/s
|
374.6 MB/
|
-5%
|
|||
| BZip2Comp ST |
5.01 MB/s
|
7.29 MB/s
|
45%
|
|||
| BZip2Comp MT |
20.5 MB/s
|
20.5 MB/s
|
0%
|
|||
| Bzip2Decomp ST |
7.99 MB/s
|
9.76 MB/s
|
24%
|
|||
| Bzip2Decomp MT |
30.8 MB/s
|
24.9 MB/s
|
-19%
|
|||
| JPG Comp ST |
18.9 MP/s
|
23.3 MP/s
|
23%
|
|||
| JPG Comp MT |
88.9 MP/s
|
76.7 MP/s
|
-14%
|
|||
| JPG Decomp ST |
41.5 MP/s
|
62.2 MP/s
|
49%
|
|||
| JPG Decomp MT |
182.7 MP/s
|
176.6 MP/s
|
-3%
|
|||
| PNG Comp ST |
1.11 MP/s
|
1.56 MP/s
|
43%
|
|||
| PNG Comp MT |
4.78 MP/s
|
4.61 MP/s
|
-4%
|
|||
| PNG Decomp ST |
17.9 MP/s
|
24.2 MP/s
|
35%
|
|||
| PNG Decomp MT |
94.1 MP/s
|
64.3 MPs
|
-32%
|
|||
| Sobel ST |
53.3 MP/s
|
86.3 MP/s
|
62%
|
|||
| Sobel MT |
248.4 MP/s
|
244.8 MP/s
|
-1%
|
|||
| Lua ST |
1.30 MB/s
|
1.59 MB/s
|
22%
|
|||
| Lua MT |
5.93 MB/s
|
4.5 MB/s
|
-24%
|
|||
| Dijkstra ST |
3.38 Mpairs/s
|
5.52 Mpairs/s
|
63%
|
|||
| Dijkstra MT |
13.7 Mpairs/s
|
13.7 Mpairs/s
|
0%
|
|||
The actual integer performance gains with GeekBench 3 are rather varied. Single-threaded results consistently show gains, ranging from a minor -5% regression for AES up to a 61% improvement for SHA2. Given the architecture shift involved here, this is a bit surprising (and in Qualcomm’s favor) since you wouldn’t necessarily expect Kryo to beat Cortex-A57 on everything. On the other hand MT results typically show a regression, since Snapdragon 810 had a 4+4 big.LITTLE configuration that meant that it had the 4 Cortex-A53 cores contributing to the task, along with the big cores all running at their near-full clockspeed, while Kryo’s second cluster runs at a reduced clockrate. And though one could have a spirited argument about whether single-threaded or multi-threaded performance is more important, I’m firmly on the side of ST for most use cases.
| Geekbench 3 - Floating Point Performance | ||||||
| Snapdragon 810 | Snapdragon 820 | % Advantage | ||||
| BlackScholes ST |
5.46 Mnodes/s
|
12.3 Mnodes/s
|
125%
|
|||
| BlackScholes MT |
25.5 Mnodes/s
|
32.1 Mnodes/s
|
26%
|
|||
| Mandelbrot ST |
1.2 GFLOPS
|
2 GFLOPS
|
67%
|
|||
| Mandelbrot MT |
6.41 GFLOPS
|
6.23 GFLOPS
|
-3%
|
|||
| Sharpen Filter ST |
1.07 GFLOPS
|
2.15 GFLOPS
|
100%
|
|||
| Sharpen Filter MT |
5.02 GFLOPS
|
6.11 GFLOPS
|
22%
|
|||
| Blur Filter ST |
1.27 GFLOPS
|
3.14 GFLOPS
|
147%
|
|||
| Blur Filter MT |
6.14 GFLOPS
|
8.84 GFLOPS
|
44%
|
|||
| SGEMM ST |
2.29 GFLOPS
|
4.09 GFLOPS
|
79%
|
|||
| SGEMM MT |
6.12 GFLOPS
|
9.19 GFLOPS
|
50%
|
|||
| DGEMM ST |
1.05 GFLOPS
|
1.95 GFLOPS
|
85%
|
|||
| DGEMM MT |
2.81 GFLOPS
|
4.53 GFLOPS
|
61%
|
|||
| SFFT ST |
1.25 GFLOPS
|
1.98 GFLOPS
|
58%
|
|||
| SFFT MT |
4.11 GFLOPS
|
5.65 GFLOPS
|
37%
|
|||
| DFFT ST |
1.03 GFLOPS
|
1.68 GFLOPS
|
63%
|
|||
| DFFT MT |
2.97 GFLOPS
|
4.76 GFLOPS
|
60%
|
|||
| N-Body ST |
486.6 Kpairs/s
|
841 Kpairs/s
|
73%
|
|||
| N-Body MT |
1.72 Mpairs/s
|
2.34 Mpairs/s
|
36%
|
|||
| Ray Trace ST |
1.84MP/s
|
2.86 MP/s
|
55%
|
|||
| Ray Trace MT |
8.16 MP/s
|
8.46 MP/s
|
4%
|
|||
GeekBench 3’s floating point results are even more positive for Snapdragon 820. There is only a single performance regression, a -3% in Mandelbrot multi-threaded. Otherwise in both MT and ST workloads, performance is significantly up. This is a prime example of where Kryo is taking better advantage of its execution units than any high-end Qualcomm SoC before it, as even holding steady (or on paper having a slight deficit) it in practice comes out significantly ahead.
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lilmoe - Friday, December 11, 2015 - link
He's not talking about clock speeds. He's talking about the whole package. Samsung has lots more experience with big.LITTLE and their implementations are far superior than competing chips on the SAME process node. Both the Exynos 5433 and the Snapdragon 808 are built on 20nm, yet the Exynos performs AND sustains its performance better than the Snapdragon.testbug00 - Sunday, December 13, 2015 - link
yes, Qualcomm's memory controller was busted. Doesn't make the A57 core any better.It's a pretty bad core compared to just about everything else ARM offers currently. A7, A9, A12/17, A53, A72. All far superior to the A57 overall.
tipoo - Thursday, December 10, 2015 - link
On Samsungs 14nm process, yeah they ran ok. But it effectively cancelled out a generation's worth of fabrication process advantage, just to be able to run the things without throttle hell.melgross - Thursday, December 10, 2015 - link
This should be interesting. Phones delivering this chip will be seen, mostly, during the April-May period. That leaves them about 4 months, on average, before the iPhone 7 with the new A10 comes out. With this behind the A9 in many areas, that doesn't give them much leeway in performance or time.So most of the year leaves Apple's chips basically unchallenged. It seems to me that shipping schedules for flagship Android phones needs to shift, along with the release of high end SoCs to more closely match Apple's release dates, or there will always be this disparity.
While it's often said that Android phone manufacturers are competing against one another more than they are competing against Apple, that's only true because they have a hard time competing against Apple at the higher end. Having phones that better compete in performance on the same release schedule would help somewhat.
This chip really needed to come out last August, not next spring.
Refuge - Friday, December 11, 2015 - link
I disagree, they have no problem competing with Apple at the high end. They won me easily.The A9 is a nice chip, but running iOS its like having Camaro SS with a limiter set at 75mph.
I'm sorry, I just can't and won't consider the two eco-systems in any way similar. People buy the OS first and the device second. Like iphone, but want an android OS? Someone has an iPhone clone out right now just for you.
mdriftmeyer - Friday, December 11, 2015 - link
Wow. The voice of one dot speaking against reality. Apple's SoC designs and implementations are only expanding their leads on the competition. That ecosystem they also dominate in is building ever greater loyalty: they deliver and the software matches the hardware.Move along and hope for the future.
mdriftmeyer - Friday, December 11, 2015 - link
Above comment should have embedded below Refuge.bug77 - Thursday, December 10, 2015 - link
Nice preview, but, as it happens lately, what matters more is sustained performance, not some burst numbers during a single benchmark run.jjj - Thursday, December 10, 2015 - link
Interesting that they seem to be going with a small cache and the memory score is rather nuts for just 2x32bit."And though one could have a spirited argument about whether single-threaded or multi-threaded performance is more important, I’m firmly on the side of ST for most use cases."
Do note that SD820 has 2 cores clocked lower, it's not just 4 vs 8, it's 4+4 vs 2+2. Everybody in the dumb press will be tempeted to forget that 2 cores are clocked lower here .
As for ST perf , the thing is that at this perf level ST is more than enough so it loses relevance. Would be nice if you guys would compare ST perf with Nehalem and newer desktop cores.
Anyway, it blows that you insist on using the same empty synthetic benchmarks that have no relevance at all. SPECint2000 and Geekbench are fine but all else is irrelevant.
"Where the 820 MDP/S makes up for it is in the photo editing score, which is through the roof. Here Qualcomm’s development device holds a 34% performance lead over the next-fastest device, the 810/A57 based Mi Note Pro."
So using the GPU or DSP? If so , is it cheating or (all) actual apps will use the GPU/DSP too, as they should. How about the behaviour of all other SoCs. Long live synthetic! It's like begging them to cheat....
"Apple’s commanding lead in ARM CPU performance."
How is that exactly? Have you actually done any math , at the very least at equal per core power? In die area Apple is far behind but you don't like that being mentioned.
In Geekbench Apple does 2.5k in each of the 3 segments, Kryo does about 2.1k in FP and integer and well over 3k in memory. So 20% higher clocks could eneble Kryo to match Apple's core in FP and integer. It's not impossible that in a dual core config Kryo could clock 20% higher. Same for A72. In the end if MTK can clock 2xA72 at 2.5GHz on 20nm, they could do much better on 16ff+. In theory 16ff+ can provide up to 40% higher speed over 20nm but only some 30% is needed. Ofc A72 is also much much smaller than Apple's core and you can actually make a cheap SoC with it for 150$ phones.
vs A72 ,it's hard to assume things. If A72 goes to 2.5 GHz in quad config and matches the SD820 in power ,then it's somewhat even and not really.
In Geekbench Kryo at 2.15 vs A72 at 2.5Ghz should be about even in integer with Kryo having some 10% lead in FP but Kryo would be at higher per core power.
You got core 3 and 4 at likely half the power (or even less) at max load, so total power is like having 3 cores at max clocks. Folks could do that with A72 too.
Ofc remains to be seen if A72 can reach 2.5GHz or even more with fewer cores and how everybody does in power.
Will be very interesting to see Kryo in server. Assuming it will be a slightly tuned Kryo and not something very different.
A72 does enable others to provide a multitude of configs in different price ranges and that could be interesting. Just today a Xiaomi device showed up in Geekbench with SD618 and just 2GB of RAM. 2GB of RAM would be too little for anything above Redmi 3 and Redmi 3 couldn't be priced above 699CNY (109$). Sure it would be dual A72 at low clocks on 28nm but it's a start.
tipoo - Thursday, December 10, 2015 - link
You're assuming it will happily clock 20% higher with no disproportionate power draw increases. This is what Qualcomm provided, so it only makes sense for the reviewer to test it as they got it, rather than speculating on what it would be while higher clocked.I don't see how Apples die area matters to an end user. The cost is spread through the entirety of the product, they are premium products, but really all that matters in the end to a user is performance and battery life.