
AMD 2nd Gen Ryzen Deep Dive - bratao
https://www.anandtech.com/show/12625/amd-second-generation-ryzen-7-2700x-2700-ryzen-5-2600x-2600
======
zelos
Have the meltdown/spectre patches really had a roughly 30% effect on
compilation performance on Intel CPUs? The i7-8700K went from 22 compiles/day
to 14.

[https://www.anandtech.com/show/11859/the-anandtech-coffee-
la...](https://www.anandtech.com/show/11859/the-anandtech-coffee-lake-
review-8700k-and-8400-initial-numbers/11)

[https://www.anandtech.com/show/12625/amd-second-
generation-r...](https://www.anandtech.com/show/12625/amd-second-generation-
ryzen-7-2700x-2700-ryzen-5-2600x-2600/13)

The fact that the i7-8700K shows up as slower than the i7-8700 now is a bit
weird too.

~~~
onli
> _The fact that the i7-8700K shows up as slower than the i7-8700 now is a bit
> weird too._

It's impossible. The 8700K and the 8700 are the same chip, just that the 8700K
has an unlocked multiplier and a higher default clock[0] - better binning. The
8700 will never be faster in any application.

[0]: [http://www.cpu-
world.com/Compare_CPUs/Intel_CM8068403358220,...](http://www.cpu-
world.com/Compare_CPUs/Intel_CM8068403358220,Intel_CM8068403358316/)

~~~
saltcured
Unlocked multipliers don't mean you've chosen the optimal multiplier. And
something binned for higher clock rates doesn't necessarily mean it runs
cooler at the same clock rate as another part. As others have mentioned,
thermal management is a real issue here. A throughput benchmark doesn't care
about brief bursts of speed, but rather sustainable rate.

Finally, even with identical parts, the assembly can affect performance. The
same heat-sink installed slightly more effectively in terms of the mechanical
interface (no contamination, just the right amount of heat-sink compound, no
air bubbles) will allow the chip to run at higher power without any thermal
throttling.

~~~
onli
I honestly would have thought that the binning/testing done on those
processors would make sure that the difference always go into the same
direction, as in more performance for the higher specced part. Because I
assume that in a benchmark just as this the cooling is sufficient to keep the
turbo clock indefinitely, meaning that it makes no difference if the 8700
without limitations would beat the 8700K. But what you and the other say
sounds convincing, maybe scenarios like this can happen in practice more
easily than I thought.

~~~
saltcured
It's a common real-world issue that someone buys the "faster" CPU option in a
laptop and finds it runs slower than their coworker's because the thermal
design and/or quality of assembly causes it to overheat and throttle.

With many systems, turbo is only a temporary burst benefit for a lightly
loaded system. Many server or HPC systems would intentionally disable turbo to
have consistent sustained throughput.

~~~
onli
Definitely. But this is not a laptop with cooling issues, in this case we are
talking about a professional benchmark setup. If cooling was an issue during
this, it would just add an other negative point to the bunch of irregularities
in this review.

------
Aissen
So it seems for now that everything is consistent with the benchmarks
published a month ago in a _paper_ magazine in France:
[https://www.cpchardware.com/cpc-hardware-36-debarque-en-
kios...](https://www.cpchardware.com/cpc-hardware-36-debarque-en-kiosque/)
(french)

What did they do differently ? They didn't ask AMD for permission or sign an
NDA for exclusive "early" access, and just sourced the parts on ebay from one
of the numerous samples that were given to ODMs/OEMs.

~~~
kbenson
Mind providing a little info on what it was they were saying that was
different than the rest (which is what I inferred you are trying to express)?

~~~
Aissen
I might not have been clear: everything they benchmarked is identical to
benchmarks that are being published now.

They just had a big head start because they acted independently and didn't
wait for vendor approval to publish their tests.

Edit: here's an english source with the magazine contents:
[http://www.guru3d.com/news-story/cpc-hardware-amd-
ryzen-7-27...](http://www.guru3d.com/news-story/cpc-hardware-amd-
ryzen-7-2700x-print-review-is-online-incl-benchmarks.html)

~~~
kbenson
Ah. To me it sounded like you were saying their benchmarks were more "honest"
and didn't contain some bias the others did because they bypassed the NDAs.
Thanks for clarifying!

------
onli
It is also in the comments, but the gaming benchmarks are really strange here.
Every new Ryzen processor beats even the fastest Intel cpu in each and every
game they benchmarked? That's highly unlikely, and completely conflicts with
the results of other, more gaming focused reviewers like GamersNexus, see
[https://www.gamersnexus.net/hwreviews/3287-amd-r7-2700-and-2...](https://www.gamersnexus.net/hwreviews/3287-amd-r7-2700-and-2700x-review-
game-streaming-cpu-benchmarks-memory/page-3). What is anandtech doing
different?

~~~
mping
On the comments: "Intel CPUs were tested with Meltdown/Spectre patches, that's
probably the discrepancy you're seeing."

~~~
onli
So every other reviewer is not using those patches (isn't Windows installing
them automatically?), and the performance impact is that huge that it
completely negates every performance advantage Intel had for now almost a
decade?

~~~
citilife
I'm not 100% sure about every other reviewer, but many times tests will be
done with a base windows 10 install (as to avoid the need to look at
comparisons between patches).

Regarding performance impact, short answer is - yes. Basically, it removes
most of the advantage of the cache for Intel.

~~~
blattimwind
> many times tests will be done with a base windows 10 install [without any
> updates/patches]

So, even without Spectre & friends, these benchmarks are essentially
meaningless?

~~~
jdietrich
It's a difficult problem. It's not practical to re-test all of the old CPUs or
GPUs every time you review a new part. Either you test all components against
a baseline OS and driver set, or you test components with whatever OS and
driver releases are contemporaneous. Neither case is ideal.

Reviewers have generally settled on the former option; OS and driver updates
tend to increase performance, so testing with contemporaneous software might
artificially inflate the apparent performance deltas in favour of newer
components. Nobody wants to buy a new processor thinking that it's 40% faster
than their old one, only to discover that most of the difference was just OS
optimisations. You'd rather have your readers be pleasantly surprised than
bitterly disappointed, so it makes sense to choose a benchmarking methodology
that errs on the side of favouring older parts.

Spectre is a weird exception to business as usual, because we saw a huge
performance _decrease_ in a single update that affects one particular
optimisation in one particular processor generation. In this case, it probably
makes sense for reviewers to re-run all of their old benchmarks and set a new
baseline.

------
fibonacci112358
Interesting for developers is the improvement in compiling Chrome, and also
the big hit from the Meltdown/Spectre patches on Intel on the same benchmark.

~~~
noir_lord
I held off upgrading my personal desktop last year (and built Ryzen 1700 for
work) then meltdown/spectre hit and I decided to wait for the 2700X, I'm glad
I did more performance at less money and without the hit that Intel took, I'll
likely build an R2700X in a month or two when any teething troubles have had
time to hit the wire.

------
zanny
Just a note these chips don't have hardware mitigations for Spectre and
Meltdown. The first Intel and AMD chips that will have had the time for them
to be implemented to offset the performance losses will be coming out next
year (Ice Lake and Zen 2 respectively). That being said, like Ars mentions in
the article, AMD chips are in general hit less by the OS patches than Intel
ones.

~~~
karavelov
For start AMD chips are nor vulnerable to Meltdown, so the impact of
mitigations is smaller as it only addresses Spectre.

------
Symmetry
Generally raising a processor's clock frequency will decrease its IPC as it
spends more time waiting for main memory, so it isn't surprising that the
overall IPC only went up 3% despite the various cache optimizations. I
wouldn't have actually been surprised if it had stayed the same. But I'm
frankly sort of amazed that they've managed to go to having consistently lower
cache latencies than Intel has. I always thought that Intel's greater
willingness to throw engineer-hours at optimizing layouts would mean they'd
always take less clock cycles to hit their caches.

~~~
sp332
I don't think IPC tests involve main memory I/O.

Edit: I missed that the benchmark methodology is on a different page from the
results.

~~~
dragontamer
An IPC test is basically running a benchmark while locking the processor's
Frequency (through overclocking tools). That way, you get to test the
architecture without dealing with all the Turbo-boost stuff on modern chips.

Memory latency / bandwidth is a piece of any benchmark. Some benchmarks are
purely CPU (Linpack), but others are better overall tests of the system (ex:
Cinebench or Blender)

------
degenerate
Here's a different benchmark (video rendering) that still places all the 8th
gen Intel chips above Ryzen 2:

[https://www.pugetsystems.com/labs/articles/After-Effects-
CC-...](https://www.pugetsystems.com/labs/articles/After-Effects-CC-2018-CPU-
Comparison-AMD-Ryzen-2-vs-Intel-8th-Gen-1137/)

I assume these tests are unpatched Intels though. Since my use case for CPU is
video rendering and not gaming, I still don't have a reason to switch to
Ryzen, as much as I want one. Threadrippers are still way out of my price
range (~$1K) and are about the same performance as top tier i7 8th gen.

~~~
d1zzy
Ultimately if all you need to use the CPU for is After Effects CC then follow
the results of that benchmark (or rather, follow the performance/$ for that
specific benchmark). Otherwise, in general the AMD CPUs give more multi-core
performance/$ than Intel, for example, in any multi-core x264 based test I've
seen. And it makes sense why that is so, the AMD CPU has more cores and more
cache for the same $. And that's only comparing CPU prices and performance, if
we consider the motherboard prices then the needle moves further into AMD's
favor.

As to why After Effects CC seems to prefer Intel so much would indicate some
specific optimizations Adobe performs, optimizations that seem to favor Intel
for now, not general raw multi-core performance of the Intel CPU.

For single core performance the situation is reversed, the higher clocked (but
lower core count) Intel CPUs will obviously have much better single core
performance which is important for games as even today they tend to be coded
relying on a few threads.

~~~
dragontamer
> As to why After Effects CC seems to prefer Intel so much would indicate some
> specific optimizations Adobe performs, optimizations that seem to favor
> Intel for now, not general raw multi-core performance of the Intel CPU.

I bet its AVX-512. Which is "Intel Specific" but that's the entire point of
AVX-512, a new Intel specific instruction set that has high performance
benefits.

Overall, AMD is betting on general purpose cores with at most 128-bits per
operation. AMD supports the AVX 256-bit instruction set, but its "emulated",
as the ALU pipelines are 128-bit (granted: AMD can gang together two ALUs in a
2x128-bit configuration to execute the 256-bit instructions)

Intel supports 3x256-bits per operation on their CPUs, with the 512-bit AVX512
instructions using two execution ports at a time.

So for any code that's written to be SIMD-heavy, Intel machines will likely be
faster. Not only because of AVX512, but also because Intel's AVX-256 bit
instructions are better supported compared to AMD (3x256-bit for Intel, vs
2x128-bit for AMD)

\------------

With that being said: the benefits of SIMD approach Ahmdal's law just like
anything else. In particular, AVX512 uses so much power that Intel cores are
forced to downclock.

So AMD can run more cores, at higher frequencies. But Intel's cores do more
work per clock tick and per unit energy. It seems like AMD's 16-cores (each
doing 2x128-bit) are only slightly slower than Intel's 10-cores (each doing
3x256-bits) in those SIMD-heavy tests.

~~~
Dylan16807
> (3x256-bit for Intel, vs 2x128-bit for AMD)

It's not quite that harsh for workloads that aren't entirely FMA. Zen has
2x128-bit adders plus 2x128-bit multipliers.

~~~
dragontamer
Fair enough. The full AMD pipeline contains 4x 128-bit execution ports. But
this is a bit complicated, so I was ignoring that part of the core.

IMO, the more important bottleneck is the load/store unit. Intel's system has
2x 256-bit loads + 1x 256-bit writes to the L1 cache.

While AMD's system has 2x128-bit load+store units for its L1 cache.

Thus my numbers above: 3x256-bit for Intel (2 reads + 1 write), while
2x128-bits for AMD (2x read-or-write).

------
chiph
I've been very happy with my 1700. There were some initial POST problems from
a memory mismatch (they are very picky, it seems) but once that was sorted
out, it's been terrific. Video encoding goes much faster than it used to. No
cooling problems with the included AMD heatsink & fan.

The questions for me are: Is it worthwhile to upgrade? And will my old memory
work in with the new CPU? (my guess would be "no")

~~~
onli
It is not worthwhile to upgrade. The difference between the Ryzen 7 1700 and
the Ryzen 7 2700 is small, the slightly higher clock and performance
improvement does not warrant an upgrade. The new processors are just a new
nice option if you are not already on a current cpu, like an old FX or a dual
core intel.

Your old memory will work with your new cpu, to 99%. AMD improved memory
compatibility with software updates, and the memory support in the 2000 line
is supposed to be better again. If your ram is slower than DDR4-2666 you lose
some performance compared to what you could have, but that was already true
for the 1700 - DDR4-3000 is a good minimal ram speed target, as Ryzen profits
a lot from being combined with faster ram.

------
monocasa
It's super weird that there weren't any RTL changes in the core. Like even in
the process part of tick/tock, you can normally sneak in some fixes. And it's
not like you can put those RTL folks on optimizing mask layouts; it's a
totally different skillset.

Are the uarch people at AMD running around with their hair on fire trying to
fix all their Spectre/et al. bugs, and skipped a release to focus?

~~~
walshemj
I think it was speed boost2 that was / is the main change and also its a
process shrink to 12nm

~~~
monocasa
Sure, but the question is, what are the other half of their staff doing of not
working on this release?

~~~
dragontamer
Playstation5, Navi GPUs, XBox's next processor, Ryzen3, 7nm Vega. There's
rumors for DDR5 memory controller and MCM reaching the GPU space somehow.

AMD's plate is rather full. They're juggling a lot of cool projects despite
having way less money than Intel or NVidia. Zen+ was always going to be a "low
effort" minor update.

I'm frankly surprised that this minor update got much of a boost at all. Its a
good sign for Zen2 next year.

------
spatular
Is there any info if linux compilation segfault (kill-ryzen) has been fixed?

Edit: and what is ECC status? Still not officially supported?

------
jlebrech
would it be worth it starting on $99 and upgrading to Ryzen 7 later on.

I was going to do that with AM3 but then they dropped the socket. and the
upgrade path is quite big here if it's all on the same socket.

~~~
zdw
AM3 and AM3+ lasted quite a while - used from new CPU's 2009-2014, which were
the high end desktop sockets from AMD until 2017.

In the same time Intel went through 4 sockets: LGA 1156 -> 1155 -> 1150 ->
1151

~~~
sliken
5 actually, there's two versions of the 1151 and they aren't compatible.

