  The use of cloud computing grows as it appears to be an additional resource
for High-Performance Parallel and Distributed Computing (HPDC), especially with
respect to its use in support of scientific applications. Many studies have
been devoted to determining the effect of the virtualization layer on the
performance, but most of the studies conducted so far lack insight into the
joint effects between application type, virtualization layer and parallelized
libraries in applications. This work introduces the concept of affinity with
regard to the combined effects of the virtualization layer, class of
application and parallelized libraries used in these applications. Affinity is
here defined as the degree of influence that one application has on other
applications when running concurrently in virtual environments hosted on the
same real server. The results presented here show how parallel libraries used
in application implementation have a significant influence and how the
combinations between these types of libraries and classes of applications could
significantly influence the performance of the environment. In this context,
the concept of affinity is then used to evaluate these impacts to contribute to
better stability and performance in the computational environment.
