AMD EPYC v Intel Xeon Scalable Taking Stock of Myths July 2017

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PigLover

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Jan 26, 2011
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Perhaps the most useful article written anywhere to date on EPYC vs Intel. Thank you.
 

ATS

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Mar 9, 2015
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Most shocking that they don't have pcie hotswap working, for Intel that's a PRQ gate.
 

Patrick

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Dec 21, 2010
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I am a bit surprised this did not get circulated more widely. Items in there that are crucial to enterprise buyers and not reported elsewhere.
 

Patrick

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Ryzen early days was rough. Now much better. Just do give you an idea we have a Ryzen 7 1700 system running Ubuntu with Kernel 4.10 that has uptime of several months now in the data center.

When we first got EPYC in June it was rough. Now it is incredibly better. The EPYC system just finished two weeks of running workloads like GROMACS, Linux kernel compiles, high-end CFD applications/ crash test simulations. Zero seg faults and we were switching from Ubuntu for our standard workloads to CentOS for the higher-end applications. Those are the simulation tools that cost many thousands of dollars per core and use AVX2 extensively as well.

AGESA updates on EPYC have been a big deal. Remember, EPYC is considerably more complex than Ryzen or TR.

It is something I personally have been struggling with. We have had almost two months with a system where I could have posted videos of bugs that I knew were getting fixed just to get more clicks. I decided that STH would not be participating in that to keep the editorial integrity high.

Then again, realistically you are not buying EPYC for another week or two for the leading edge of shipments.

Feel free to post this on the /r
 

zir_blazer

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Dec 5, 2016
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AGESA updates on EPYC have been a big deal. Remember, EPYC is considerably more complex than Ryzen or TR.
I'm already on the camp of the people that believes that x86 is so obscenely complex that is nearly impossible to debug all the possible edge cases. Intel themselves ocasionally have an elusive errata, and their architectural changes have not been as dramatic as AMD going from a mature Excavator to first generation Zen.
What I'm personally worried about while I bite my fingernails, is how much time it takes for them to fix these things that ocasionally pop, because in a worst case scenario it could be a Hardware bug that can't be fixed by microcode, or incurs a hefty performance penalty like the Barcelona TLB bug. I'm quite confident that AMD will fix things as quick as possible and probably in a year no one will remember what early Ryzen was like, but as I can't get into a cryostasis chamber, I'l have to go through this emotional rollercoaster while I cross my fingers that all these things will get fixed.

The other problem is that there are a whole bunch of people that are already rather biased against AMD or considers them a second class manufacturer, basically, those conservative people in the "No one got fired for buying IBM" camp that currently goes Intel only (I can't blame them after Bulldozer!). These potentially minor issues are making that some people gets a bad early impresion, and it is rather hard to convince them to go AMD when you have several Threads in Linux communities complaining about the segfaults on Ryzen, even through sometimes Intel has its screws up, too. But these hurts AMD much more.
I wish that AMD could pull out a perfect launch...
 

( )

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Jul 8, 2017
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When we first got EPYC in June it was rough. Now it is incredibly better. ... Then again, realistically you are not buying EPYC for another week or two for the leading edge of shipments.
I know the feeling, early days are sometimes rough and it can be a challenge to determine if it's the Processor, Motherboard, Software, or lack of coffee.

While I've waited years for the AMD CPUs of this year to come I'm currently convinced to await Zen 2 (7 nm); at least it will also afford me a peek at POWER9 Systems.

When I was a Tech (decades ago) there wasn't a Computer on Earth as powerful as what sits on some people's desks today.

The explosion of technology is a dream come true for some (I reap the benefits without working 12-14 hour days) and a tax on the mind for others.

Over at TheNextPlatform they did an Article on this yesterday, I thought you might be interested in the 8-Way Interconnect Diagram they made:

intel-skylake-xeon-system-topologies.jpg
 

Patrick

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Dec 21, 2010
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That is the official Intel diagram of 8S. The big part is that each CPU only has connections to 3 peers.

Rome is going to be the big one.
 
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Evan

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Jan 6, 2016
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The limitations of the 8S config won't be felt my many, not much these days that needs 8S vertical scaling. 4S is not even that common except for some DB servers and a few other odd uses. (E.g. We have some CFD type functions that make more sense on a single 4S machine rather than a number or 2S machines even thought the workload is parallel the application is just easier to manage on a single large machine. (No interconnects etc to care about)