[boost] Write data to NAND flash file system

Hi, I am using boost::filesystem to write / remove files to NAND flash file system where it writes by pages, the system can cache and pack data upon write back to avoid segmentation if fsync(), fdatasync(), O_SYNC or a sync mounted filesystem are not used to force write. Will the boost::filesystem::ofstream and operator<< involve any of sync call? Which IO library is not using sync call? Thank you. Kind regards, - jupiter