Я не почем эта настройка не используется по умолчанию. На серверах это критично может улучшить перформанс. На домашних компах это тоже не помешает.
"It's also perhaps the most stupid Unix design idea of all times. Unix is really nice and well done, but think about this a bit: 'For every file that is read from the disk, lets do a ... write to the disk! And, for every file that is already cached and which we read from the cache ... do a write to the disk!'" (Ingo Molnár, Red Hat)
