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An EPYC NixOS Build Farm

grahamc.com

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Re: An EPYC NixOS Build Farm

#31

Post by grhmc »

chris_st wrote: post #30
aseipp wrote: post #27

Earlier quoted context omitted.

It's our custom tool. NixOS has testing infrastructure built on top of QEMU, and you can use Perl scripts like this in order to automate aspects of testing inside that environment by talking to the QEMU monitor -- for example, you can not only wait for a window, but click a button in that window, then also wait for a service to start afterwords, for example. (If you were testing GUI functionality). Tests are written…

Thanks very much for this information (you and @grhmc). PLEASE consider releasing some form of this tool, or at least documenting the snot out of it... it looks incredible. We'd really use this at work.

I think it would be really difficult to get such a good experience with something that isn't NixOS. You might look at things like:

- http://open.qa/ - TestKitchen

But I must recommend, indeed, taking a good hard took at NixOS! :)

Re: An EPYC NixOS Build Farm

#32

Post by dezgeg »

chris_st wrote: post #30
aseipp wrote: post #27

Earlier quoted context omitted.

It's our custom tool. NixOS has testing infrastructure built on top of QEMU, and you can use Perl scripts like this in order to automate aspects of testing inside that environment by talking to the QEMU monitor -- for example, you can not only wait for a window, but click a button in that window, then also wait for a service to start afterwords, for example. (If you were testing GUI functionality). Tests are written…

Thanks very much for this information (you and @grhmc). PLEASE consider releasing some form of this tool, or at least documenting the snot out of it... it looks incredible. We'd really use this at work.

The internals of the test framework are pretty heavily tied to Nix and NixOS, so a release independent of Nix(OS) isn't probably going to happen. With that said, the test infrastructure itself is exposed as library functions that any Nix user can use. And even though the test VMs itself will run NixOS, the host machine can be any Linux distro with Nix installed.

Re: An EPYC NixOS Build Farm

#33

Post by cjhanks »

They are testing performance of a heavily modified and secure Xen type 1 hypervisor against a native computer with unspecified security policies?

This seems like a meaningless measurement.

Re: An EPYC NixOS Build Farm

#34

Post by bearjaws »

newnewpdro wrote: post #23

This is comparing far more than Xeon vs. EPYC, not even a single mention of the storage subsystem on these respective machines. It's not like the tasks being timed are 100% CPU-bound...

On the other hand, the EPYC server is 50% less per month so I believe it is showing how much more you can get for less $.

Re: An EPYC NixOS Build Farm

#35

Post by praseodym »

bearjaws wrote: post #34
newnewpdro wrote: post #23

This is comparing far more than Xeon vs. EPYC, not even a single mention of the storage subsystem on these respective machines. It's not like the tasks being timed are 100% CPU-bound...

On the other hand, the EPYC server is 50% less per month so I believe it is showing how much more you can get for less $.

The EPYC server only has a quarter of the RAM though, so it’s really apples vs. oranges to compare prices directly.

Re: An EPYC NixOS Build Farm

#36

Post by ksec »

uluyol wrote: post #28
ksec wrote: post #21

Earlier quoted context omitted.

>They are effectively getting 35% extra performance 60% of the price that's just beyond impressive. Lets just ignore the price point for now because the memory capacity are different. But the performance, 24 Core AMD EPYC Zen is ~35% faster than 24 Core Intel Broadwell Xeon under the same frequency? Broadwell isn't even that old because Intel has only launched Skylake Xeon E5 not long ago. And the different between S…

I suspect that the Xeon processors are running at a lower frequency under load compared to the EPYC ones. That's just a hunch though.

It isn't, because according to the spec sheet its all Core frequency are about the same as AMD.

Re: An EPYC NixOS Build Farm

#37

Post by mrb »

boris wrote: post #3
tmd83 wrote: post #2

This is quite surprising. I assumed they would get an EPYC server with higher core at similar price (due to the cost of the CPU) and get advantage in performance/dollar. I didn't expect EPYC to beat a similar physical core count intel server running at similar core count let alone by this much margin. Am I missing something here? I'm saying this as someone who really wants AMD to succeed and push the ecosystem forwar…

EPYC is compared to a previous generation Xeon with lower TDP (105w vs 155/170w) and slower RAM (2400 vs 2666). The Xeon server is more expensive probably because it has 4x the amount of RAM. Edit: actually, this is a dual Xeon machine so its TDP is slightly higher than EPYC's.

«EPYC is compared to a previous generation Xeon»

That's not enough to explain. I highly doubt replacing the 12-core Broadwell Xeon CPUs with a current-generation 12-core Xeon (which would be Skylake) would catch up with the 30-40% performance lead that EPYC displays in their workload.

The Zen microarchitecture of the EPYC is quite impressive and it could just very well be a workload that Zen is particularly good at.

For example the fact EPYC can pack so many cores on a single socket means all the RAM and all its 64MB of last-level cache are "local" to every core (at worst accesses go through the Infinity Fabric.) By comparison, in Intel's case when one of the Xeon cores need to access RAM or cache on the other socket, accesses have to go through the QPI link between the 2 sockets, and it has higher latencies and worse throughput than AMD EPYC's Infinity Fabric.

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