On Sun 19-01-20 09:17:00, yukuai (C) wrote: > > > On 2020/1/17 19:05, Jan Kara wrote: > > provide > > allocation for each page separately > > Thank you for your response! > > I do understand there will be additional CPU overhead. But page is allocated > in __do_page_cache_readahead(), which is called before > iomap_begin(). And I did not change that. Sorry, I didn't express myself clearly. In "...one of the big points of iomap infrastructure is that you call filesystem once to give you large extent instead of calling it to provide allocation for each page separately." I meant that with your patch, you call into filesystem to provide "block allocation information" for each page separately. And it seems we both agree this is going to cause additional CPU usage in the common case to improve mostly unsupported corner case. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
