The OpenPOWER Saga Continues: Can You Get POWER Inside 1U?
by Johan De Gelas on February 24, 2017 8:00 AM ESTEnergy Consumption
We know that the POWER8 was not designed to be a performance-per-watt champion. Throughput, single threaded performance, and RAS were the main priorities. However, Tyan does position the GT75 as a virtualization server. In that market, performance-per-watt is important.
We tested the energy consumption of our servers for a one-minute period in several situations. The first one is the point where the tested server performs best in MySQL: the highest throughput just before the response time goes up significantly. Then we look at the point where throughput is the highest (no matter what response time). This is the situation where the CPU is fully loaded.
The final column is calculated by dividing the best throughput by the power usage. We define the "best throughput" as throughput where the balance between throughput and the 95th percentile response time is the best. In other words, beyond that point, throughput increases only slightly (less than 10%), but the response time increases much faster.
| SKU | Server Height | TDP (on paper) spec |
Idle Server W |
MySQL Best Throughput at Lowest Resp. Time (*) (W) |
MySQL Max Throughput (W) |
Transaction /s (**) |
Tr/watt ( = ** / * ) |
| IBM POWER8 8c@2.3 Tyan | 1U | 170 W | 171 | 323 | 330 | 10300 | 32 |
| IBM POWER8 10c@2.9 S812LC | 2U | 190 W | 221 | 259 | 260 | 14482 | 55 |
| Xeon E5-2699 v4 | 2U | 145 W | 67 | 213 | 235 | 18997 | 89 |
| Xeon E5-2640 v4 | 2U | 90 W | 76 | 135 | 145 | 9541 | 71 |
| Xeon E5-2690 v3 | 2U | 135 W | 84 | 249 | 254 | 11741 | 47 |
At idle, both of the POWER8-based servers reduce their clockspeed to 2.06 GHz and power-gate the cores they do not need. However, the Tyan GT75 PSU is probably more efficient in this case, and the GT75 is a less complex server as well. As a result, the idle power is significantly lower than the S812LC. Still, it is nowhere near the Intel Xeons.
Once we test the server under load, the Tyan GT75 demands a lot more power than the S812LC. That might seem contradictory at first sight, as the latter is equipped with more power hungry CPU. The main culprits are the small, extremely high RPM 1U fans inside the Tyan, which have to work hard to keep a 170W CPU cool in such a cramped environment.
Notice how the IPMI software reports 8800 RPM, but in reality the fan is running at a mindboggling 15600 RPM. A total of twelve such fans results in the cooling system as a whole consuming a lot of power.
This kind of "performance first" CPU policy really needs larger fans and more room. Case in point: in a roomier 2U chassis the load power consumption of a POWER8 setup comes very close to the contemporary 22 nm Xeon E5 v3. It will be interesting to see how this works out in the 1.25U high Rackspace BarrelEye.
Intel's "Broadwell-EP" (Xeon E5 v4) wins here by an vast margin. And there is little doubt that the next generation Skylake Xeons will probably do (slightly?) better.
However, don't count IBM and OpenPOWER out yet. First of all, MySQL is better optimized for x86-64 than for POWER8. Since MySQL is the second most popular database engine (and will probably overtake Oracle soon), we feel our choice is justified. However, it is worth mentioning that PostgreSQL (number 4) and MongoDB (5) have been fully optimized for OpenPOWER and show gains of up to 30%. Lastly, IBM's POWER9 should also do quite a bit better as a result of an improved microarchitecture and being baked with a state-of-the art 14 nm SOI process. The 14 nm POWER9 versus the "tweaked 14 nm" Intel Xeon E5 version 5 should prove a very interesting comparison.
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Einy0 - Friday, February 24, 2017 - link
Articles like these make me wonder if some of these companies using IBM eServer iSeries(AS/400) as mid-level servers are wasting their money. I was always under the impression that Power was suppose to be tuned for database heavy workloads and hence have a massive advantage in doing so. I know the iSeries servers run an OS with DB2 built-in and tuned specifically for it but how much of an advantage does that really equate to?FunBunny2 - Friday, February 24, 2017 - link
-- I know the iSeries servers run an OS with DB2 built-in and tuned specifically for it but how much of an advantage does that really equate to?unless IBM has done a complete port recently, AS/400 "integrated database" was built before server versions of DB2 existed. it's/was just a retronym.
kfishy - Friday, February 24, 2017 - link
As ISAs becoming more and more relevant in the post-Moore's law world, where you can't solve a computational problem just by throwing ever more transistors at it, I wonder if this opens up opportunity for POWER to carve out niches left out by Intel's more fixed and general purpose approach.At the same time, POWER will have to contend with a nascent but rising and truly open ISA in RISC-V, where companies can simply implement the subsets of the ISA that they need. The next decade in processor architecture is going to be interesting to watch.
FunBunny2 - Friday, February 24, 2017 - link
-- As ISAs becoming more and more relevant in the post-Moore's law world, where you can't solve a computational problem just by throwing ever more transistors at itgiven that ISA has been reduced to z, ARM, and X86 not counting Power, of course. and ARM might not really qualify as equivalent. for those ancient enough, or well read enough, know that up to and during the "IBM and 7 Dwarves" era, ISA and even base architecture, made a varied ecosystem. not so much anymore. and I doubt anyone will invent a more efficient adder or multiplier or any other subunit of the real CPU. just look at the screen shots of chips over the last couple of decades: the real CPU area of a chip is nearly disappeared. in fact, much (if not most) of the transistor budget for some years has been used for caching, not ISA in hardware. so called micro-architecture is just a RISC CPU, and the rest of the chip is those caches and ever more complicated "decoder". that and integrating what had previously been other-chip functions. IOW, approaching monopoly control of compute.
I expect the next decade to be more of the same: more cache and more off-chip function brought on chip. actual CPU ISA, not so much.
aryonoco - Saturday, February 25, 2017 - link
Thank you Johan. Great article.Not all AnandTech articles live up to the standards set in the days past, but your articles continue your own excellent standards.
Very much looking forward to POWER 9 chips. Hopefully they have also done the work to port the toolchain and important software already to it this time and we won't have to wait another 12 months after release to be able to compile normal Linux programs on it.
Also, 12 fans running at 15,000 rpm in a 1U? What did that sound like?! Wow!
JohanAnandtech - Sunday, February 26, 2017 - link
Thx Aryonoco. Not all of those 12 fans were running at top speed, but imagine a Jumbo jet taking off sound. It clearly show how hard it is to cool IBM's best in a 1U: you have to limit the clockspeed to about 2/3 of what it is capable off and double the number of fans.yuhong - Wednesday, March 1, 2017 - link
"Unfortunately, the latest 8 Gbit based DIMMs are not supported."Micron don't make these chips anymore:
http://media.digikey.com/pdf/PCNs/Micron/PCN_32042...
Interestingly, Crucial is selling 32GB DDR3 quad rank RDIMMs again (but not LR-DIMMs):
http://www.crucial.com/usa/en/ct32g3erslq41339
mystic-pokemon - Sunday, March 5, 2017 - link
For folks who are saying that POWER only looks good on paper. NOT true.I know shit ton of stuff about one of the server Johan listed above. He has a point when he says Power consumption is only so much important.
In short, when you combine all aspects to TCO model: POWER8 server delivers most optimal TCO value
We consider all the following into our TCO model
a) Cost of ownership of the server
b) Warranty (Lesser than conventional server, different model of operations)
c) What it delivers (How many independent threads (SMT8 on POWER8 remember ? 192 hardware threads), how much Memory Bandwidth (230 GBPs), how much total memory capacity in 1 server ( 1 TB with 32 GB)
d) For a public cloud use-case, how many VMs (with x HW threads and x memory cap / bw ) can you deliver on 1 POWER8 server compared to other servers in fleet today ? Based on above stats, a lot .
e) Data center floor lease cost in DC ( 24 of these servers in 1 Rack, much denser. Average the lease over age of server: 3 years ). This includes all DC services like aggers, connectivity and such.
f) Cost per KWH in the specific DC ( 1 Rack has nominal power 750W)
All this combined POWER has good TCO. Its a massively parallel server, what where major advantage comes from. Choose your workload wisely. That's why companies continue to work on it.
I am talking about all this without actually combining with CAPI over PCIe and openCAPI. With POWER9 all this is getting even better. Get it ? POWER is going no where.