On 2020/7/5 17:12, Matthias Ferdinand wrote: > 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, Hi Matthias, Thank you for the input. > > 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 > Yes I plan to define a very limited minimum configuration set. And rested should be configured via user space tool. > 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. Yeah, I think in the same way as yours. Coly Li
