not sync the file. The exception is the sg io engine, which
synchronizes the disk cache anyway.
-overwrite=bool If writing to a file, setup the file first and do overwrites.
+overwrite=bool If true, writes to a file will always overwrite existing
+ data. If the file doesn't already exist, it will be
+ created before the write phase begins. If the file exists
+ and is large enough for the specified write phase, nothing
+ will be done.
end_fsync=bool If true, fsync file contents when the job exits.