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AMD 3rd Gen EPYC Milan Review

anandtech.com

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Re: AMD 3rd Gen EPYC Milan Review

#81

Post by ece »

bryanlarsen wrote: post #23

Hopefully they can fix their idle power consumption with a firmware tweak or a new stepping, that's a massive regression. It looks like that causes a significant performance degradation too -- more of the power budget going to IO means less to the compute cores.

> ...The core-to-core latency within a quadrant this generation has improved from a worst-case 112ns to 99ns, about a 10ns improvement. Access to remote quadrants has been reduced from up to 142ns to up to 114ns, which is actually a 24% improvement, which is considerable.

> What’s really interesting is that inter-socket latencies have also seen very notable reductions. Whereas the Rome part these went up to 272ns, the new Milan part reduces this down to 202ns, again a large 25% improvement between generations.

Good I/O is going to have a cost in terms of die area and power. Granted what Anandtech observed is interesting for 2P systems. Maybe there's a NPS4 vs NPS1 difference at work here, or AMD just isn't doing as much power gating on the IOD as it could in one or either case.

Re: AMD 3rd Gen EPYC Milan Review

#82

Post by greggyb »

ChuckNorris89 wrote: post #7
rbanffy wrote: post #5

Why so little L3 cache on the competition?

Limitations due to die size and power consumption since Intel Xeon is still on the ye olde 14nm++ process. Also since Xeon dies are monolithic, unlike AMDs chiplet design, means that increasing the size of certain components on the die, like cache for example, increases the risk of defects wich reduces the yields, making them unprofitable.

FYI, 'ye olde' is actually using the letter 'y' to represent an Old English 'thorn' character. The thorn character represents the 'th' sound. Printing presses gained prominence in non-English speaking regions earlier than in English speaking regions. The 'y' was substituted for the 'thorn' due to some amount of similarity in shape.

Thus, 'ye olde' would be pronounced 'the old'. 'Ye' is just a different form of 'the' from a time when 'y' represented 'th'.

So, 'the ye olde' would be read as 'the the olde'.

Re: AMD 3rd Gen EPYC Milan Review

#83

Post by dragontamer »

mattashii wrote: post #80
dragontamer wrote: post #71

Earlier quoted context omitted.

SPEC benchmarks are hardly synthetic. They're Perl programs like SpamAssassin, or GCC-compile times, and other "server-like" tasks. So one can maybe argue that those workloads don't match your use case. But... SPECINT is the "standard server benchmark" for a reason. I think there's been some suggestions that SPEC benchmarks are a bit small these days and maybe bigger code would be more realistic. But the actual progr…

> SPEC benchmarks are hardly synthetic. They're Perl programs like SpamAssassin, or GCC-compile times, and other "server-like" tasks. That I didn't know. SPEC doesn't really do much in regards to giving descriptive names to benchmarked items, so its hard to determine what the numbers indicate (other than "this benchmark, which emulates some workload, now has X higher performance"). Some names are descriptive-ish (I t…

https://www.spec.org/cpu2017/Docs/benchmarks/500.perlbench_r...

Among other benchmarks. But Perl is the first one in their suite.

EDIT: SPECjbb is the Java benchmark suite: https://www.spec.org/jbb2015/docs/designdocument.pdf

SPECjbb is a ~2 hour benchmark simulating a high-throughput Supermarket backend.

Re: AMD 3rd Gen EPYC Milan Review

#84

Post by greggyb »

modzu wrote: post #2

how is a 300W cpu cooled in a server environment? just high rpms and good environmentals? ive stayed on intel with my workstation so i can keep a virtually passive and quiet heatsink without having to go water

Don't forget that you could feasibly use a 280W 64-core processor to replace a dual-socket 2x205W 2x28-core Intel box with 8 cores to spare. Obviously, there will be performance deltas based on specific use cases, but this should help frame the comparison.

Re: AMD 3rd Gen EPYC Milan Review

#85

Post by derefr »

dragontamer wrote: post #75
derefr wrote: post #69

Earlier quoted context omitted.

Rather than buying new-old-stock CPUs, why not just buy all the CPUs the long-term program will ever need when they're still cheap, and stockpile them? It's not like they go bad.

There are exceptions of course, but computers are a depreciating asset. You should never buy more computers than you need at any given time, because next year offers better computers for cheaper. Similarly: don't "invest" into a car. They also depreciate. In contrast: artwork, houses, and a few other goods (Magic: The Gathering cards?) seem to appreciate... or increase in price. These stuff you want to buy before the…

Yes, but isn't this exactly one of those exceptions?

You need this exact model of X, Y, and Z, because those have been validated as a working combination through a huge one-time capital expenditure; and changing anything would entail going through that again.

Vendors tend to not mark down prices for components, but rather just sell them for MSRP for as long as they can, and then immediately stop producing the item. The margins on each component were usually thin enough that there's no way to sell the component any cheaper but "make it up in volume." It's either "sell it at the MSRP" or "don't produce it at all."

As such, the only place to get the component after the original vendor ceases production, is the secondary market, e.g. new old stock. This is where you see governments buying old 5.25" floppy disks for huge markups.

In that case, like I said, why not just buy all the 5.25" floppies you'll ever need in advance? They know they'll be using them for 50 years, because that's the decomissioning schedule for the system they just built, and they'll be unlikely to ever get budget to replace/upgrade it before then. They also know how long a floppy lasts in use. So, do the math, buy that many floppies early, and toss them all in an airless vault. Right?

And the same thing would be true here with particular-model CPUs, no?

Re: AMD 3rd Gen EPYC Milan Review

#86

Post by wmf »

eqvinox wrote: post #78

Kinda wish there was a 3rd gen 7282 equivalent, for those of us just building their home servers. 2 sockets with (... really need to replace my 2×E5-2630v2, it's getting quite old... but I guess a 2×7282 will do.) [Ed.: nevermind, hadn't read to the "idle consumption" graphs yet... nope, I'll stick with Rome ...]

Why would two weak sockets be better than a single-socket system?

Re: AMD 3rd Gen EPYC Milan Review

#87

Post by wffurr »

coder543 wrote: post #54
wffurr wrote: post #36

Earlier quoted context omitted.

RTFA: “ Users will notice that the 16-core processor is more expensive ($3521) than the 24 core processor ($2900) here. This was the same in the previous generation, however in that case the 16-core had the higher TDP. For this launch, both the 16-core F and 24-core F have the same TDP, so the only reason I can think of for AMD to have a higher price on the 16-core processor is that it only has 2 cores per chiplet ac…

I really don't think the article's speculation there is helpful... it's really reaching. As I said below the article in the comments: > If I were to speculate, I would strongly guess that the actual reason is licensing. AMD knows that more people are going to want the 16 core CPUs in order to fit into certain brackets of software licensing, so AMD charges more for those to maximize profit and availability of the 16 c…

It's definitely not a typo.

Re: AMD 3rd Gen EPYC Milan Review

#88

Post by bsoft16385 »

kllrnohj wrote: post #45
unicornfinder wrote: post #34

Earlier quoted context omitted.

Performance per watt is better but unfortunately the idle power consumption is fairly high.

Epyc's idle power consumption is fairly high but Ryzen's isn't. The more workstation-focused Threadripper & Threadripper Pro is also still significantly better than Epyc here.

Zen2/Zen3-based, non-APU Ryzen still has pretty awful idle power consumption compared to Intel desktop CPUs.

My 5900X at idle draws around 22W. Modern Intel desktop CPUs (which are basically all Skylake refreshes right now) are 8-10W at idle.

Re: AMD 3rd Gen EPYC Milan Review

#89

Post by fomine3 »

kllrnohj wrote: post #45
unicornfinder wrote: post #34

Earlier quoted context omitted.

Performance per watt is better but unfortunately the idle power consumption is fairly high.

Epyc's idle power consumption is fairly high but Ryzen's isn't. The more workstation-focused Threadripper & Threadripper Pro is also still significantly better than Epyc here.

Is TR Pro really better? I suspect that it's just difference between motherboard because it's basically same as EPYC.

Re: AMD 3rd Gen EPYC Milan Review

#90

Post by jedbrown »

wmf wrote: post #86
eqvinox wrote: post #78

Kinda wish there was a 3rd gen 7282 equivalent, for those of us just building their home servers. 2 sockets with (... really need to replace my 2×E5-2630v2, it's getting quite old... but I guess a 2×7282 will do.) [Ed.: nevermind, hadn't read to the "idle consumption" graphs yet... nope, I'll stick with Rome ...]

Why would two weak sockets be better than a single-socket system?

16 channels of DDR4-3200, versus 8 in single socket EPYC or 4 for Threadripper.
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