SAPonPower

An ongoing discussion about SAP infrastructure

POWER10 – Opening the door for new features and radical TCO reduction to SAP HANA customers

As predicted, IBM continued its cycle of introducing a new POWER chip every four years (after a set of incremental or “plus” enhancements usually after 2 years).[i]  POWER10, revealed today at HotChips, has already been  described in copious detail by the major chip and technology publications.[ii]  I really want to talk about how I believe this new chip may affect SAP HANA workloads, but please bear with me over a paragraph or so to totally geek out over the technology.

POWER10, manufactured by Samsung using 7nm lithography, will feature up to 15 cores/chip, up from the current POWER9 maximum of 12 cores (although most systems have been shipping with chips with 11 cores or fewer enabled).  IBM found, as did Intel, that manufacturing increasingly smaller lithography with maximum GHz and maximum core count chips was extremely difficult. This resulted in an expensive process with inevitable microscopic defects in a core or two, so they have intentionally designed a 16-core chip that will never ship with 15 cores enabled. This means that they can handle a reasonable number of manufacturing defects without a substantial impact to chip quality, simply be turning off which ever core does not pass their very stringent quality tests.  This will take the maximum the number of cores in all systems up proportionately based on the number of sockets in each system.  If that was the only improvement, it would be nice, but not earth shattering as every other chip vendor also usually introduces more or faster cores with each iteration.

Of course, POWER10 will have much more than that.  Relative to POWER9, each core will feature 1.5 times the amount of L1 cache, 4x the L2 cache, 4x the TLB and 2x general and 4x matrix SIMD.  (Sorry, not going to explain each as I am already getting a lot more geeky than my audience typically prefers.). Each chip will feature over 4 times the memory bandwidth and 4x the interconnect bandwidth.  Of course, if IBM only focused on CPU performance and interconnect and memory bandwidths, then the bottleneck would naturally just be pushed to the next logical points, i.e. memory and I/O.   So, per a long-standing philosophy at IBM, they didn’t ignore these areas and instead built in support for both existing PCIe Gen 4 and emerging PCIe Gen 5 and both existing DDR4 and emerging DDR5 memory DIMMS, not to mention native support for future GDDR DIMMs.  And if this was not enough, POWER10 includes all sorts of core microarchitecture improvements which I will most definitely not get into here as most of my friends in the SAP world are probably already shaking their heads trying to understand the implications of the above improvements.

You might think with all of these enhancements, this chip would run so hot that you could heat an Olympic swimming pool with just one system, but due to a variety of process improvements, this chip actually runs at 3x the power efficiency of POWER9.

Current in-memory workloads, like SAP HANA, rarely face a performance issue due to computational performance.  It is reasonable to ask the question whether this is because these workloads are designed with an understanding of the current limitations of systems and avoid doing more computationally intense actions to avoid delivering unsatisfying performance to users who are increasingly impatient with any delays.  HANA has kind of set the standard for rapid response so delivering anything else would be seen as a failure.  Is HANA holding back on new, but very costly (in computational terms) features that could be unleashed once a sufficiently fast CPU becomes available?  If so, then POWER10 could be the catalyst for unleashing some incredible new HANA capabilities, if SAP takes advantage of this opportunity.

A related issue is that perhaps existing cores can deliver better performance, but memory has not been able to keep pace.  Remember, 128GB DRAM DIMMS are still the accepted maximum size by SAP for HANA even though 256GB DIMMS have been on the market for some time now.  As SAP has long used internal benchmarks to determine ratios of memory to CPU, could POWER10 enable to the use of much more dense memory to drive down the number of sockets required to support HANA workloads thereby decreasing TCO or enabling more server consolidation?  Remember, Power Systems all featured imbedded, hardware/hypervisor based virtualization, so adding workloads to a system is just a matter of harnessing any unused extra capacity.

IBM has not released any performance projections for HANA running on POWER10 but has provided some unrelated number crunching and AI projections.  Based on those plus the raw and incredibly impressive improvements in both the microarchitecture and number of cores, dramatic cache and TLB increases and gigantic memory and interconnect bandwidth expansions, I predict that each socket will support 2 to 3 times the size of HANA workloads that are possible today (assuming sufficient memory is installed).

In the short term, I expect that customers will be able to utilize TDI 5 relaxed sizing rules to use much larger DIMMs and amounts of memory per POWER10 system to accomplish two goals.  For customers with relatively small HANA systems, they will be able to cut in half the number of sockets required compared to existing HANA systems.  For customers that currently have large numbers of systems, they will be able to consolidate those into many fewer POWER10 sytems.  Either way, customers will see dramatic reductions in TCO using POWER10.

As to those customers that often run out of memory before they run out of CPU, stay tuned for part 2 of this blog post as we discuss perhaps the most exciting new innovation with POWER10, Memory Clustering.

 

[i] https://twitter.com/IBMPowerSystems/status/1295382644402917376
https://www.linkedin.com/posts/ibm-systems_power10-activity-6701148328098369536-jU9l
https://twitter.com/IBMNews/status/1295361283307581442
[ii] Forbes – https://www.forbes.com/sites/moorinsights/2020/08/17/ibm-discloses-new-power10-processer-at-hot-chips-conference/#12e7a5814b31
VentureBeat – https://venturebeat.com/2020/08/16/ibm-unveils-power10-processor-for-big-data-analytics-and-ai-workloads/
Reuters – https://www.reuters.com/article/us-ibm-samsung-elec/ibm-rolls-out-newest-processor-chip-taps-samsung-for-manufacturing-idUSKCN25D09L
IT Jungle – https://www.itjungle.com/2020/08/17/power-to-the-tenth-power/

 

August 17, 2020 - Posted by | Uncategorized | , , , , , , , ,

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