What exactly is a "virtual core" on Amazon EC2?

Question

The small Standard Instance is:

Small Instance (Default) 1.7 GB of memory, 1 EC2 Compute Unit (1 virtual core with 1 EC2 Compute Unit), 160 GB of local instance storage, 32-bit or 64-bit platform

Does this mean that you get access to an entire physical CPU core? Or are you sharing a more powerful core with other instances?

Is your performance affected by other people sharing the same "physical core" or other hardware?

Solution 1

You don't get a physical core for a small instance.

"One EC2 Compute Unit provides the equivalent CPU capacity of a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor. This is also the equivalent to an early-2006 1.7 GHz Xeon processor referenced in our original documentation." Amazon EC2 Instance Types

You can run cat /proc/cpuinfo to see what hardware you're on. For example I have a micro instance which has the underlying processor Intel(R) Xeon(R) CPU E5430 @ 2.66GHz.
From my understanding 40% cpu in top equals 1 Compute Unit. So I can burst to 80% with my 2 Compute Unit's.

Solution 2

this is rough estimate so take it for what its worth. Funny enough the micro instance out preformed both the small & medium instances.

I ran Passmark Proformance Test 8.0 on each instance below. Each was installed with Windows Server 2008 r2 basic config in Amazon's Virginia based data center.

AWS SIZE=======PASSMARK SCORE====SIMILAR SCORED CPU================
t1.micro=======963===============AMD Dual-Core Mobile ZM-80========
m1.small=======384.7=============Intel Celeron M 1.60GHz===========
m1.medium======961===============AMD Dual-Core Mobile ZM-80========
m1.large=======1249==============Intel Core2 Duo T6400 @ 2.00GHz===
m1.xlarge======3010==============AMD Phenom 2 X4 12000=============
m3.xlarge======3911==============Intel Xeon X5365 @ 3.00GHz========
m3.2xlarge=====6984==============Intel Xeon E3-1220 V2 @ 3.10GHz===

Currently the m3.2xlarge would cost about $7169 pr year for a reserved instance or $1578 pr month on an on-demand instance. Most unmanaged dedicated hosting companies I've seen offer Intel Xeon E3-1200 setups for around $2000-2500 pr year. In my opinion AWS is great for scalability but very costly for anything long-term. As seems to be the case with any "cloud" based server systems.

------UPDATE Here is a great tool for measuring cloud hosting benchmarks.. http://cloudharmony.com/benchmarks

Solution 3

http://www.cpubenchmark.net/high_end_cpus.html If look at this table 1 EC2 Compute unit ≈ 350 cpu points

Solution 4

Please go through these blogs to get an idea of virtual cores.Very well explained http://www.pythian.com/blog/virtual-cpus-with-amazon-web-services/ http://samrueby.com/2015/01/12/what-are-amazon-aws-vcpus/

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