Hello Shuo,
Have you compared the performance of an unmodified Genode system (e.g., qt5.run) with VSOS? I have compared the performance of an unmodified Genode system (both 13.02 and 14.08) and VSOS both on qemu and real machine. The performance of them are similar which cannot satisfy our team leader/my advisor. He thought that it should be faster for apps on Genode (all operations should be finished at once), but both unmodified Genode and VSOS cannot satisfy him. He thought the problem may be related to inter-process communication between Init and ,or interaction between Qt and other parts of Genode, but I don't find out the problem in these aspects.
your observation surprises me. We have recently compared the performance of Arora (using Qt5, not Qt4!) running on the Pandaboard by measuring page-load times of large websites like spiegel.de. We found that Arora running on the base-hw kernel was actually faster than Arora running on the current version of Ubuntu Linux.
Have you considered to cross-correlate the performance issues using different kernels? E.g., running the qt5.run script on NOVA instead of Fiasco.OC? Some workloads are known to be extremely slow on Fiasco.OC. See [1] for more details.
[1] https://github.com/genodelabs/genode/issues/712
Also, it might be worth considering to test the scenarios on a different hardware platform and revisit the BIOS settings for power-management.
Finally, I'd like to reinforce what Vasily just said. Please provide us with a metric for "good" performance.
Best regards Norman