Could an EC2 machine to 4 times slower than local dev workstation?

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Could an EC2 machine to 4 times slower than local dev workstation? Mark Kerzner 12/29/11 8:20 PM
Hi,

I am running a small program to load about 1 million rows into HBase. It
takes 200 seconds on my dev machine, and 800 seconds on a c1.medium EC2
machine. Both are running the same version of Ubuntu and the same version
of HBase. Everything is local on one machine in both cases.

What could the difference between the two environments be? I did notice
that my local machine has higher CPU loads:

hbase 64%
java (my app) 38%
hdfs 20%

whereas the EC2 machine
hbase 47%
java (my app) 23%
hdfs 14%


Sincerely,
Mark

Re: Could an EC2 machine to 4 times slower than local dev workstation? Amandeep Khurana 12/29/11 9:38 PM
Is your client program running on the same node? Given that c1.mediums are
on shared hosts, your neighbor might be overloading his VM, causing yours
to starve.
Re: Could an EC2 machine to 4 times slower than local dev workstation? Bryan Beaudreault 12/30/11 8:54 AM
We have also seen this in our testing, though we focused mainly on MR more
than HBase.

Keep in mind that EC2 Compute Units are defined as follows:

The amount of CPU that is allocated to a particular instance is expressed
> in terms of these EC2 Compute Units. We use several benchmarks and tests to
> manage the consistency and predictability of the performance of an EC2
> Compute Unit. One EC2 Compute Unit provides the equivalent CPU capacity of
> a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor.


This does not even account for CPU contention that Amandeep mentioned,
which we have noticed at times as well.  Also, c1.mediums have a I/O
Performance rating of "Moderate."  I think this mainly refers to ethernet
speed, but it could refer to disk speed as well.

If your local workstation is a reasonably modern system, it is very
possible for you to see much better performance locally.  The difference
between 2.5 1.0 GHz 2007 processors (2.5 compute units) and a modern i5,
i7, or equivalent is huge not just in speed and number of cores, but
architecture, cache, etc.  In terms of HBase write speed, if you are
running on an SSD this could cause a substantial gap as well.

Re: Could an EC2 machine to 4 times slower than local dev workstation? Michel Segel 12/30/11 10:28 AM
Hi,
Yes the performance hit is normal.
Looks like you're seeing network latency on disk I/O.
Could also be a tuning issue. (differences in configurations...)

Not sure how much. CPU difference will impact performance, while disk I/O will really kill you.


Sent from a remote device. Please excuse any typos...

Mike Segel

On Dec 30, 2011, at 11:33 AM, Mark Kerzner <mark.k...@shmsoft.com> wrote:

> Thank you, Bryan,
>
> that is very important and clear some cloudiness in my mind.
>
> Sincerely,
> Mark

Re: Could an EC2 machine to 4 times slower than local dev workstation? S Ahmed 5/15/12 4:45 PM
any ideas how many c1.mediums might be on a given physical server? (rough
ideas...)

On Fri, Dec 30, 2011 at 12:36 AM, Li Pi <l...@idle.li> wrote:

> Yup. Virtualized IO pretty much explains it.
>
> On Thu, Dec 29, 2011 at 8:20 PM, Mark Kerzner <markk...@gmail.com>
Re: Could an EC2 machine to 4 times slower than local dev workstation? Andrew Purtell 5/15/12 5:04 PM
It's not just a matter of having neighbors, and anyway > 0 neighbors
is a performance problem. You'll note in the numbers below that the
local machine had higher CPU use. I expect this was because it was
getting more work done given the lower latency and higher throughput
of non-virtualized IO.
Re: Could an EC2 machine to 4 times slower than local dev workstation? Doug Meil 5/15/12 7:10 PM

For the record, what Andrew/Li said is pretty much the standard disclaimer
in the Performance chapter for EC2.  It's a separate class of performance
problem.

http://hbase.apache.org/book.html#perf.ec2