[HH] cores: AMD vs Intel

Wed Mar 13 06:50:59 EDT 2013

There are some comparisons on Phoronix from a while back... like these...

http://www.phoronix.com/scan.php?page=article&item=amd_bulldozer_gcc47
http://www.phoronix.com/scan.php?page=news_item&px=MTE5Mzk

there are so many classifications now what with rankings like Green Graph500 and HPEC Challenge... you can probably find a system of benchmarks that fit your programming model or architecture best. General Purpose computing seems to be disappearing as a priority... probably because most folks never used their architecture for more than one primary applications...

On Mar 13, 2013, at 3:29 AM, Tom Metro wrote:

> Federico Lucifredi wrote:
>> Any nice comparison of per-core performance between AMD and Intel?
> 
> Do you literally want a comparison that looks at the performance of an
> individual core, in isolation?
> 
> The comparisons I've seen uses the usual benchmarks, which attempt to
> emulate real-world usage, and thus they're impacted by the imperfect way
> tasks are distributed to multiple cores, and memory bandwidth, etc.
> 
> What's your application?
> 
> 
>> Because, looking at the FX processors six and eight core prices, they
>> are nowhere near what a 6 core Intel chip costs… so i'd like to educate
>> myself on the why.
> 
> The short answer is they're cheaper because they perform considerably
> worse. At least that's what I've read.
> 
> I don't recall a specific comparison, but at some point I read one at
> Anandtech or Tom's Hardware.
> 
> Here's one:
> http://www.anandtech.com/show/6396/the-vishera-review-amd-fx8350-fx8320-fx6300-and-fx4300-tested
> 
>  Last year's launch of AMD's FX processors was honestly disappointing.
>  The Bulldozer CPU cores that were bundled into each Zambezi chip were
>  hardly power efficient and in many areas couldn't significantly
>  outperform AMD's previous generation platform. Look beyond the direct
>  AMD comparison and the situation looked even worse. In our conclusion
>  to last year's FX-8150 review I wrote the following:
> 
>    "Single threaded performance is my biggest concern, and compared to
>    Sandy Bridge there's a good 40-50% advantage the i5 2500K enjoys
>    over the FX-8150. ..."
> 
> Here's a thread linking to reviews comparing the FX-6300 to the i3:
> http://www.tomshardware.com/forum/id-1623327/6300-gaming.html
> 
> 
> The problem with these sites is that they review with desktop or gaming
> performance in mind. What I wanted to know about was VM performance.
> Can, for example, you attain better performance per dollar running 8 VMs
> on an AMD 8-core CPU than you can on a 4-core i7?
> 
> 
> In other CPU news, I see...
> 
> Calxeda's ARM server tested
> http://www.anandtech.com/show/6757/calxedas-arm-server-tested
> 
>  At first sight, the relatively low performance per core of ARM CPUs
>  seems like a bad match for servers. The dominant CPU in the server
>  market is without doubt Intel's Xeon. The success of the Xeon family
>  is largely rooted in its excellent single-threaded (or per core)
>  performance at moderate power levels (70-95W). Combine this
>  exceptional single-threaded performance with a decent core count and
>  you get good performance in almost any kind of application.
>  [...]
>  Having four 32-bit Cortex A9 cores, each with 32 KB instruction and 32
>  KB data L1 per-core caches, the processor block is somewhat similar to
>  what we find inside modern smarphones. One difference is that this SoC
>  contains a 4MB ECC enabled L2 cache, while most smartphone SoCs have a
>  1MB L2 cache.
>  [...]
>  A dual Xeon E5 or Opteron 6300 server has much more processing power
>  than most of us need to run one server application. That is the reason
>  why it is not uncommon to see 10, 20 or even more virtual machines
>  running on top of them.
>  [...]
>  Each server node has one quad-core Cortex A9 with 4MB of L2 cache and
>  4GB of RAM. With that being the case, the question "what can this
>  server node cope with?" is a lot more relevant.
>  [...]
>  The ARM based server is a pretty bad choice right now for memory
>  intensive workloads. Even with four cores and DDR3-1333, the useable
>  bandwidth is less than one sixth of what one Xeon core can sustain.
> 
>  In a similar vein, the ECX-1000 is not capable of providing more
>  bandwidth than an Atom system equipped with DDR2-667. However, both
>  the Atom and ARM cores are pretty bad when it comes to bandwidth.
>  [...]
>  Clock for clock, the out-of-order Cortex-A9 inside the Calxeda
>  EXC-1000 beats the in-order Atom core. A single A9 has no trouble
>  beating the older Atoms while likewise coming close to the much higher
>  clocked N2800. The N2800 and ECX-1000 perform similarly.
>  [...]
>  Looking at both decompression and compression, it looks like a quad
>  ARM A9 is about as fast as one Xeon core (without Hyper-Threading) at
>  the same clock. We need about six A9 cores to match the Xeon core with
>  Hyper-Threading enabled. The quad-core ECX-1000 1.4GHz is also close
>  to the dual-core, four-threaded Atom at 1.86GHz. This bodes well for
>  Calxeda as the 6.1W S1240 only runs at 1.6GHz.
>  [...]
>  We created 24 virtual machines on top of the Xeon server. ...
>  [Calxeda's] server gets the same workload, but instead of using
>  virtual machines, we used the 24 physical server nodes.
>  [...]
>  At the low concurrencies, the Intel machine leverages turboboost and
>  its exceptionally high per core performance. At the higher web loads,
>  the total throughput of the 96 (24x quad-core SoCs) ARM A9 cores is up
>  to 50% higher than the low power 32 thread/16 core (2x Octal core)
>  Xeons. Even the mighty 2660 cannot beat the herd of ARM SoCs.
>  [...]
>  ...each server needs about 8.3W (200W/24), measured at the wall. That
>  is exactly what Calxeda promised: about 6W (at 1.4GHz) per server node
>  (measured internally), up to 8.5W measured at the wall (again at
>  1.4GHz). That is nothing short of amazing if you consider the
>  performance numbers.
>  [...]
>  Let's be clear: most applications still run better on the Xeon E5. Our
>  CPU benchmarks clearly indicate that any application that accesses the
>  memory frequently or that needs high per thread integer processing
>  power will run better on the Xeon E5. Compiling and installing
>  software simply feels so much faster on the Xeon E5, there is no need
>  to benchmark.
> 
> (See the article for lots more details.)
> 
> The 8-core AMD parts may be useful in a similar way to the ARM parts,
> except the AMD parts tend to get dinged for power consumption, even
> compared to the higher performing Intel parts. So even if they do make
> sense in this context, it won't be long before the ARM servers take over
> that space.
> 
> -Tom
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