Summary:
This patch does the following improvement on the regression_test.sh
* allows db_bench being executed at a remost host while storing the
benchmark results locally.
* kills all db_bench related processes before running db_bench
* better error handling.
Test Plan:
1. Run regression_test.sh both locally and remotely
2. Run multiple regression_test.sh at the same time and make sure
i. Only one runs successfully.
ii. The one that runs successfully will kill all other db_bench
processes before it runs any benchmark.
Reviewers: sdong, yiwu, gunnarku
Reviewed By: gunnarku
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D58611