Summary:
After 7f6c02dda16471c2ed3318e9e7156f2b8d13bf46, the same get_perf_context() is called both of internally and externally. However, I found internally this is not got inlined. I don't know why this is the case, but directly referencing perf_context is the logical way to do.
Closes https://github.com/facebook/rocksdb/pull/2892
Differential Revision: D5843789
Pulled By: siying
fbshipit-source-id: b49777d8809f35847699291bb7f8ea2754c3af49