On Mon, Sep 21, 2020 at 11:09:48PM +0800, Coly Li wrote:

I feel this is something should be fixed. Indeed I overlooked it until
you point out the issue now.

The optimal request size and read ahead pages hint are necessary, but
current initialization is simple. A better way might be dynamically
setting them depends on the cache mode and some special configuration.

By your inspiration, I want to ACK your original patch although it
doesn't work fine for all condition. Then we may know these two settings
(ra_pages and queue_io_opt) should be improved for more situations. At
lease for most part of the situations they provide proper hints.

How do you think of the above idea ?

Sounds like a plan.  I'd reall like to get this series in to get
some soaking before the end of the merge window, but we should still
have plenty of time for localized bcache updates.