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Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

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Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#41

Post by kev009 »

berkut wrote: post #40
floren wrote: post #9

Earlier quoted context omitted.

Do you have actual benchmarks of x86 vs. Power 9 or are you just talking out your ass?

For well-optimised floating point calculations, this is generally true (even taking into account the SMT capabilities of Power8). Intel also has 8-wide (and more) SIMD in terms of intrinsics (AVX/AVX512), whilst Power is still limited to 4-wide with AltiVec, although with Power9 VSX should allow wider (I think). Where Power8/9 really shines is memory bandwidth - it's orders of magnitude faster than leading edge Intel…

AVX512 will severely clock throttle an intel chip. I only want to see real world tests on a workload when comparing the two.

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#42

Post by dragontamer »

berkut wrote: post #40
floren wrote: post #9

Earlier quoted context omitted.

Do you have actual benchmarks of x86 vs. Power 9 or are you just talking out your ass?

For well-optimised floating point calculations, this is generally true (even taking into account the SMT capabilities of Power8). Intel also has 8-wide (and more) SIMD in terms of intrinsics (AVX/AVX512), whilst Power is still limited to 4-wide with AltiVec, although with Power9 VSX should allow wider (I think). Where Power8/9 really shines is memory bandwidth - it's orders of magnitude faster than leading edge Intel…

Power systems also have an absurdly sized L3 cache. Case in point: Power9 is advertised to have 120MB of L3 cache.

I'm sure there are a lot of problems that fit inside of 120MB.

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#43

Post by marshray »

YawningAngel wrote: post #35
marshray wrote: post #26

Earlier quoted context omitted.

IBM will never understand this but few, if any, architectures have made it into the datacenter that were not first affordable for experimenters and enthusiasts. The burden of proof is on those claiming the pricing does not present a barrier to entry to the ecosystem. I am curious about developing for Power. Please link me to an entry-level system I can buy on the web.

Why does it matter what enthusiasts use? There are piles of Enterprise software written in Java that can be shifted to any architecture you care to name on a moment's notice. Lots of Java shops would bite your hand off if offered a 20% price cut for instances in exchange for switching architectures.

> Why does it matter what enthusiasts use?

A. Many of the people who today specify datacenter hardware came into that career as enthusiasts (aka "early adopters") and are more comfortable recommending what they have experience with.

B. Enthusiasts bring the consumer volume that drives down production cost. This is a necessary driver of Moore's law.

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#44

Post by dragontamer »

opencl wrote: post #38
aseipp wrote: post #29

Earlier quoted context omitted.

They definitely aren't charging 10X for it, it's very much in line and competitive at the Xeon level in terms of pricing, and they shine for certain workloads, especially with the new interconnects (CAPI, NVLink). POWER8 was harder to find, but the performance characteristics were good (in my experiments). And now the software is better (more solid ports) and cost is down. I'm eagerly awaiting the chips to hit this y…

The mobo+single quad core CPU is $2,475, that's way more than the threadripper setup and the threadripper has 4x the core count.

Threadripper also only has 8MB of L3 cache per CCX, and you can't hold more than 8MB of data. (true, there are 4x CCX per chip, but you can't "combine" the datasets. You're effectively limited to 8MB per 4-cores. To communicate cross-CCX requires an expensive ping to main-memory) Its a great architecture, but cross-CCX communication is relatively slow and definitely is a concern for some work problems.

Power9 has 120MB of L3 cache that's shared between all cores. Which means you can ACTUALLY have a full 120MB-sized problem set and share all that information between cores.

In short: Threadripper is great for sure, but its not necessarily a fair comparison. In an apples-to-apples comparison (ie: Monero Mining), it seems like a Power9 server is 3x better than Threadripper (Power9 gets ~3000 hash/sec, while Threadripper is roughly 1000 hash/sec).

https://www.phoronix.com/scan.php?page=news_item&px=POWER9-C...

> Using the xmr-stak-power PPC64LE-focused Monero miner, they are seeing great performance with it running on dual pre-production 16-core POWER9 processors. There's a hash rate of 2945H/s while this POWER9 system is pulling 350 Watts DC power.

And mind you: Monero / Cryptonight only uses 2MB of L3 per core. So that's practically Threadripper's ideal problem. Imagine if you actually had a dataset that was larger than the 8MB per CCX that Threadripper is limited to.

Not to hate on Threadripper at all. Its cheap and high performance. I'm seriously considering a Threadripper system myself. But these Power9 specs are incredible, and I'd definitely like to test one if I could afford one.

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#45

Post by slededit »

opencl wrote: post #38
aseipp wrote: post #29

Earlier quoted context omitted.

They definitely aren't charging 10X for it, it's very much in line and competitive at the Xeon level in terms of pricing, and they shine for certain workloads, especially with the new interconnects (CAPI, NVLink). POWER8 was harder to find, but the performance characteristics were good (in my experiments). And now the software is better (more solid ports) and cost is down. I'm eagerly awaiting the chips to hit this y…

The mobo+single quad core CPU is $2,475, that's way more than the threadripper setup and the threadripper has 4x the core count.

The cores are not directly comparable. The Power chip has significantly more hyper threads (and the resources to back them).

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#46

Post by classichasclass »

berkut wrote: post #40
floren wrote: post #9

Earlier quoted context omitted.

Do you have actual benchmarks of x86 vs. Power 9 or are you just talking out your ass?

For well-optimised floating point calculations, this is generally true (even taking into account the SMT capabilities of Power8). Intel also has 8-wide (and more) SIMD in terms of intrinsics (AVX/AVX512), whilst Power is still limited to 4-wide with AltiVec, although with Power9 VSX should allow wider (I think). Where Power8/9 really shines is memory bandwidth - it's orders of magnitude faster than leading edge Intel…

Near as I can determine, VSX in POWER9 is still 128-bit.

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#48

Post by berkut »

kev009 wrote: post #41
berkut wrote: post #40

Earlier quoted context omitted.

For well-optimised floating point calculations, this is generally true (even taking into account the SMT capabilities of Power8). Intel also has 8-wide (and more) SIMD in terms of intrinsics (AVX/AVX512), whilst Power is still limited to 4-wide with AltiVec, although with Power9 VSX should allow wider (I think). Where Power8/9 really shines is memory bandwidth - it's orders of magnitude faster than leading edge Intel…

AVX512 will severely clock throttle an intel chip. I only want to see real world tests on a workload when comparing the two.

Yes, but even when throttled, it can often be faster than full-clock less wide instructions, if your workload allows for it. So it's sometimes worth it and there is a benefit.

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#49

Post by classichasclass »

shrumm wrote: post #15

From what I’ve read, POWER was affected by spectre/ meltdown too. However, Intels initial response to play down it’s significance can’t have gone well with large enterprise customers. In addition to the performance boosts the article refers to, I wonder how much of an impact the recent kerfuffle over Intels response had on POWER demand.

IBM already released patches for this, at least for POWER7+. Interestingly the Meltdown issue seems "only" to affect the L1 cache, so L2 does not need to be evicted. Raptor says all Talos systems will be patched prior to shipping.

https://wiki.raptorcs.com/wiki/Speculative_Execution_Vulnera...

Re: Power 9 May Dent X86 Servers: Alibaba, Google, Tencent Test IBM Systems

#50

Post by berkut »

classichasclass wrote: post #46
berkut wrote: post #40

Earlier quoted context omitted.

For well-optimised floating point calculations, this is generally true (even taking into account the SMT capabilities of Power8). Intel also has 8-wide (and more) SIMD in terms of intrinsics (AVX/AVX512), whilst Power is still limited to 4-wide with AltiVec, although with Power9 VSX should allow wider (I think). Where Power8/9 really shines is memory bandwidth - it's orders of magnitude faster than leading edge Intel…

Near as I can determine, VSX in POWER9 is still 128-bit.

I'd heard rumours... Nothing concrete though, so I could be wrong.
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