I recently had cause to run GNS3 on Linux as I needed to support a cloud interface using VLANs: I needed to link connections to some virtual routers out onto a physical interface, with each link as a separate VLAN. OS X doesn't support this (it seems - you can configure it, but it doesn't appear to work), whereas Linux does.
More on that later, but I found this guide very useful for setting up GNS3 on Ubuntu 14.04 Desktop and it worked fine in a VMware VM on my laptop:
http://www.firstdigest.com/2014/12/gns3-1-2-1-installation-on-ubuntu-14-04/
