On Sun, Jul 05, 2020 at 12:45:41PM +0800, Coly Li wrote: > While I am thinking about this, I do appreciate your help about the > input on which configuration item should be stored in the on-disk > superblock. Hi, my use case is rather limited, all my bcache devices run in writeback mode, and the only parameters I keep playing with are writeback_percent and sequential_cutoff. My short list of favourites: - cache_mode - writeback_percent - sequential_cutoff But I vaguely remember that I used rebooting as last resort after too much fiddling with tunables; persisting them in the superblock means losing this reset-to-defaults method. Would be nice to have some other way of resetting. An alternative to modifying the superblock might be something more out-of-band like iptables does with iptables-save and iptables-restore: convert current settings to text, e.g. on shutdown or at regular intervals, and restore settings on boot from this text file. Regards Matthias
