Sync all segments before acquiring the semaphore, otherwise waiting may have to wait for the timer to kick in and push them down. Note that we can't guarantee that no other requests were executed in the mean time, so we have to sync again. Signed-off-by: Glauber Costa <glauber@scylladb.com> Message-Id: <aea019fe49820acce5d2b55dd5ec31e975b3436c.1480388674.git.glauber@scylladb.com>