ARM A53/A57/T760 investigated - Samsung Galaxy Note 4 Exynos Review
by Andrei Frumusanu & Ryan Smith on February 10, 2015 7:30 AM ESTConclusion
Samsung's System LSI business had a rough two years as their decision to go with ARM's big.LITTLE SoC architecture cost them a lot of market share, thanks in part to immature software and implementation issues. Usually in the past Samsung's own Exynos SoCs were regarded as the more performant variant given the choice of Qualcomm's Scorpion CPU based solutions. This changed as the Exynos 5410 came out with a malfunctioning CCI, crippling the chip to the most battery inefficient operating mode of big.LITTLE.
Qualcomm's Snapdragon 800 capitalized on the new 28nm HPM manufacturing process, along with the advantage of being able to offer an integrated modem solution, and has dominated the market ever since. It's only now that Samsung is able to recover as the new 20nm manufacturing process allowed them to catch up and start to offer their own Exynos SoC in more variants of its products, a trend that I expect to continue in Samsung's future lineup.
The Note 4 with the Exynos 5433 is the first of a new generation, taking advantage of ARM's new ARMv8 cores. On the CPU side, there's no contest. The A53 and A57 architectures don't hold back in terms of performance, and routinely outperform the Snapdragon 805 by a considerable amount. This gap could even widen as the ecosystem adopts ARMv8 native applications and if Samsung decides to update the phone's software to an AArch64 stack. I still think the A57 is a tad too power hungry in this device, but as long as thermal management is able keep the phone's temperatures in reign, which it seems that it does, there's no real disadvantage to running them at such high clocks. The question is whether efficiency is where it should be. ARM promises that we'll be seeing much improved numbers in the future as licensees get more experience with the IP, something which we're looking forward to test.
On the GPU side, things are not as clear. The Mali T760 made a lot of advancements towards trying to catch up with the Adreno 420 but stopped just short of achieving that, leaving the Qualcomm chip a very small advantage. I still find it surprising that the Mali T760 is able to keep up at all while having only half the available memory bandwidth; things will get interesting once LPDDR4 devices come in the next few months to equalize things again between competing SoCs. Also ARM surprised us with quite a boost of GPU driver efficiency, something I didn't expect and which may have real-world performance implications that we might not see in our synthetic benchmarks.
It's the battery life aspect that I think it's most disappointing to me. It's a pity that Samsung didn't go through more effort to optimize the software stack in this regard. When you are able to take advantage of vertical integration and posses multi-billion dollar semiconductor manufacturing plants with what seem to be talented SoC design teams, it's critical to not skimp out on software. I might be a bit harsh here given that the battery disadvantage was just 12% in our web-browsing test and might be less in real-world usage, and the GPU battery efficiency seems neck-and-neck. Still, it's the wasted potential from a purely technical perspective that is disheartening.
This is definitely a wake-up call to ARM and their partners as well. If the software situation of big.LITTLE isn't improved soon I'm fearing that ship will have sailed away, as both Samsung and Qualcomm are working on their custom ARMv8 cores.
So the question is, is it still worth to try and get an Exynos variant over the Snapdragon one? I definitely think so. In everyday usage the Exynos variant is faster. The small battery disadvantage is more than outweighed by the increased performance of the new ARM cores.
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Sonicadvance1 - Tuesday, February 10, 2015 - link
"The overall increase in cache helps to improve performance, though perhaps more importantly the larger instruction cache helps to offset the larger size of the 64-bit ARM instructions."This is incorrect. AArch64 has a 32bit instruction length just like ARMv7.
Unless of course you were comparing to 16bit Thumb instructions. Vague in either case.
jjj - Tuesday, February 10, 2015 - link
Wish you would have included power numbers for A15 and A7 on 28nm since that's the more common process for A15/A7 and it's unlikely we'll see them much on 20nm and bellow (to be clear, not saying that you should have excluded the numbers on 20nm).Said this before, very curious about the encryption gains in actual use for both power and perf so maybe you guys look at that at some point. And maybe include https sites in the web browsing battery tests- tests that are kinda fuzzy on the methodology, maybe you've detailed it somewhere and i just don't remember.
The process scaling is surprising, maybe TSMC did better,we'll have to see.
Any clue how A53 power scales at much higher clocks, obviously not from this testing. Wondering how it would perform at very high clocks vs a lower clocked A57. At.1.3GHz the A53 seems to use some 3 times less power than A57 and given it's die size if it could go to 2.5Ghz on 20nm it would be interesting, at least from a cost perspective.
Andrei Frumusanu - Tuesday, February 10, 2015 - link
I only have a S4 with an 5410 at disposition, and that is running cluster migration and it's a very old chip by now. The only other candidates would have been the 5422 S5 variant which I don't posses, or to have to destroy the unibody shells of my Huawei devices to be able to do a proper power measurement.I did overclock the A53, but above 1.5GHz it's not worth running the little cores as the voltage rise is too high and the A57's at low frequency are more efficient. This is highly dependent on the core implementation, I imagine MediaTek's SoCs with high clocked "little" cores are much better optimized in such scenarios.
jjj - Tuesday, February 10, 2015 - link
Thanks for the reply.I kinda like the A53 perf at 1.5GHz and above ,nice little core and nice boost for the market it's addressing. In this SoC it does seem that above 900MHz the power goes up a lot.
Devo2007 - Tuesday, February 10, 2015 - link
Interesting to see the PCMark numbers, and how Lollipop seems to help. Given that Lollipop overall "feels" smoother, it makes sense there would be something that would allow that to be somewhat measurable.Running an early build of CM12 on my Snapdragon Note 3, and I'm seeing numbers nearly on-par with the Nexus 5 shown here.
Pissedoffyouth - Tuesday, February 10, 2015 - link
I'm running CM12 on my Note right from from an early Temasek build. Absolutely love it, and there aren't too many showstopping bugs.I hope they do put note 3 on this graph.
Devo2007 - Tuesday, February 10, 2015 - link
Yup! Teamasek 7.5.1 as of today for me (was on 7.4 when I wrote that post). Absolutely loving it now, and feel comfortable using it as my daily driver.Ranger101 - Tuesday, February 10, 2015 - link
This is the most interesting and relevant technical read I have had for some time.An excellent article.
Well done Messrs Frumusanu and Smith.
juicytuna - Tuesday, February 10, 2015 - link
Monster of an article. Will take me many rereads to take it all in.This is what Anandtech is all about, this is what separates it from the rest.serendip - Tuesday, February 10, 2015 - link
Excellent article, I really appreciate the in-depth analyses on the differences between the Exynos and SnapDragon SOCs. I'm shaking my head at Samsung's mad product line though. They seem to make a different variant for each region with so many SOC/modem/RF combinations.Wouldn't it be better to have just one or two variants supporting most of the LTE frequencies out there? I would hate to be the person at Samsung in charge of software updates for these phones. You would need a huge developer team to keep track of per-device changes and fixing bugs while keeping the code consistent along the same model line.