Improving The Exynos 9810 Galaxy S9: Part 2 - Catching Up With The Snapdragon
by Andrei Frumusanu on April 20, 2018 9:00 AM EST- Posted in
- Mobile
- Samsung
- Smartphones
- Exynos 9810
- Exynos M3
- Galaxy S9
Conclusion
With these pieces I wanted to see what’s possible with the Exynos 9810. There’s definitely still room for improvement; I’m still sure a properly tuned WALT configuration like on the Snapdragon 845 S9 or the Pixel 2 would further improve the performance or battery life of the Exynos S9. I didn’t want to go down that rabbit hole for a custom kernel, for now the improved PELT changes are just as good as it reasonably gets.
One thing I did discover is the performance discrepancy between the M3 and Kryo 385 when it comes to synthetic benchmarks versus some of the web benchmarks. While 1794 MHz is enough to match the A75-based CPU cores of the Snapdragon in GeekBench or SPEC, I wasn’t able to match the higher performance in the web benchmarks unless I raised the clocks to around 2.3GHZ. I can now dismiss software as being the main culprit here, and instead there’s more fingers pointing at the micro-architecture of the M3. This has some relatively big repercussions as it begs the question of what kind of workload is actually more representative of overall Android smartphone use-cases.
The above graphic is my best guess on what the performance/power curves look like. These are based on scheduler cost tables, voltage curves and correlations to actual measured power on certain points. The big question here is what is the actual representative positioning between the two architectures in terms of performance? As we saw in part 1, the M3 can win on average in workloads such as SPEC at the same performance points as the S845. However to reach the higher performance of the 845 in web workloads we need to raise the clocks, and this of course would shift the efficiency curves around with a much bigger favour towards the Arm cores. The average is probably somewhere in-between, and Arm and Samsung hopefully have a more complete view in terms of workload characterization.
What is indisputable is that the M3 lags behind in the lower frequency states. Here, Samsung’s cores just stop scaling further down in voltage after 1170MHz, while the Snapdragon and Arm cores' power curves are just a lot steeper. Again the absolute difference is arguable depending on workloads, be it 25% or 100%. Unfortunately at this point we’re talking about insurmountable physics and there’s just no software optimisation which will overcome this.
In the end the Exynos S9 was hampered on two fronts: one being just a very unoptimised BSP (Board support package; kernel, drivers, etc) by S.LSI (With the Mobile Division also possibly being a factor), particularly the seemingly senseless chasing of higher synthetic benchmarks scores such as GeekBench. which in turn backfired very badly in any real-world workloads. Qualcomm provided Samsung with an excellent baseline BSP on the S845 S9’s – so for S.LSI not being able to do the same is just unfortunate. The other front where the Exynos S9 was hampered was that the M3 just seems oversized and power hungry, and it can’t sufficiently act as the efficient workhorse for general workloads. Compounding problems, this comes at a cost of battery life. Here there’s just a lot more to be done to fix the efficiency and the performance discrepancy relative to Arm’s cores.
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Andrei Frumusanu - Saturday, April 21, 2018 - link
It's not a replacement; they serve different purposes.The_Assimilator - Saturday, April 21, 2018 - link
A single tech writer with some smarts is able to do what a tech conglomerate with multiple billions of dollars can't. That is absolutely fucking pathetic on Samsung's part; I used to think they were just incompetent, but to be able to design and fab their own CPUs, yet not provide appropriate working drivers for that CPU? Words quite honestly fail me.BurntMyBacon - Monday, April 23, 2018 - link
An alternate view is that they have great teams for chip design (though perhaps not as much this one), semi-conductor fabrication, and phone hardware integration., but not particularly good (being kind) teams for their software/firmware development.johnnycanadian - Saturday, April 21, 2018 - link
And the verdict is ... if you want the best Android experience, either pick up a Pixel 2 XL or wait a few months for the P3. If you want the highest performing smartphone, tolerate Apple and the never-quite-works-properly Siri and their gimmicky fashion-first business model. I expected better out of Samsung ... The Note9 is supposed to be quite an evolution ... hopefully enough that I can be convinced to trade in my Note5. As for everyday use, my Pixel 1 XL is still running brilliantly and there simply isn't enough of a performance delta to risk a third-party Android build that may or may not receive OS updates 24 months from now.santz - Saturday, April 21, 2018 - link
thank you for the excellent writeup. I just hope the Note 9 will not have exynos for their international version.Seattletech - Sunday, April 22, 2018 - link
Sign me up for2 M3
2 A75
4 A55
N Zaljov - Sunday, April 22, 2018 - link
Magnificent article, thanks for wrapping everything up in such a detailed manner.The more I‘m looking at it, the more I‘m asking myself: „WTF were they smoking when they came up with the ingenieus idea of putting all Meerkat cores into a single clock- & voltage-domain?“. And tbh, even today I can‘t come up with a proper explanation other than „Time to market & saving xtors for the sake of not blowing up the chips budget“.
Quantumz0d - Sunday, April 22, 2018 - link
Another majestic one. As expected from the initial experiment, though I was under the remark that the custom tuning would at least fix up the issue a bit, it did but the performance/efficiency is just bad. Very bad for such a high profile flagship device.A pity that this level of SoC should need 4000Mah capacity. It would have been much better for tuning and custom software enthusiasts and considering the constant high performance the voltage/power scaling is fine so vs the SD845 this SoC won't kill the total endurance of the battery fast. That's the only good thing of 9810 custom tuned/stock vs 845. But the XDA developer community and the top devs will get much more resources to work with with ease on the other phones with 845 platform like Pixel 3 or OP6 (Unfortunate Notch B$) don't have hopes on HTC as their 10 was a fail even with optimization the efficiency was off small battery and WiFi issues. OP3(T) and 5T seem the best choice for now.
Much thanks Andrei for this, superb analysis and thanks for letting us know about the EAS too, that was total gold. I needed that. I guess I will pass this. I don't want another 6hr SOT, OP3 barely has 3-5 and 6 is super bad with custom tuning that too after a gap of 1Yr. Will wait for the next Exynos if it has a headphone jack / OP7.
And please keep this work coming going forth, don't leave us in the dark, Ofc it would be great if you get a good opportunity but we need you.
Thank you again Andrei.
Azurael - Sunday, April 22, 2018 - link
On my OnePlus 5, I go from 11 hours SOT (with the standard setup) to about 7 (using EAS+schedutil) and performance in most benchmarks regresses - it clearly needs a lot of work.Spoelie - Sunday, April 22, 2018 - link
Doesn't seem like someone on XDA is picking up this config yet - would love to try it on my S9.