Description of problem:
There are many places in glusterfs code, where we can do minor improvements to handle CPU cycles better.

* No need for memset().
* Initializing large array!
* revisit locked regions, and see if it can be optimized.
* Reduce call to library functions, instead  cache some results.
* other such minor improvements, which would help overall performance.

Version-Release number of selected component (if applicable):
master


Expected results:
With focus on such improvement, we expect better CPU utilization, which means better performance in the long run.

Additional info:
This bug can be a tracker bug, and hence this shouldn't be closed as long as we feel we have good performance.