On Wed, Dec 30, 2020 at 08:08:15AM +0800, Ming Lei wrote: > It is observed that __block_write_full_page() always submit bio with size of block size, > which is often 512 bytes. > > In case of sequential IO, or >=4k BS random/seq writeback IO, most of times IO > represented by all buffer_head in each page can be done in single bio. It is actually > done in single request IO by block layer's plug merge too. > > So check if IO represented by buffer_head can be merged to single page > IO, if yes, just submit single bio instead of submitting one bio for each buffer_head. There is some very weird formatting in here. From a very quick look the changes look sensible, but I wonder if we should spend so much time optimizing the legacy buffer_head I/O path, rather than switching callers to saner helpers.
