On Thu, Oct 18, 2018 at 03:15:04PM +0200, Michal Hocko wrote: >On Thu 18-10-18 21:04:29, Wei Yang wrote: >> This is not necessary to save the pfn to page->private. >> >> The pfn could be retrieved by page_to_pfn() directly. > >Yes it can, but a cursory look at the commit which has introduced this >suggests that this is a micro-optimization. Mel would know more of >course. There are some memory models where page_to_pfn is close to free. > >If that is the case I am not really sure it is measurable or worth it. >In any case any change to this code should have a proper justification. >In other words, is this change really needed? Does it help in any >aspect? Possibly readability? The only thing I can guess from this >changelog is that you read the code and stumble over this. If that is >the case I would recommend asking author for the motivation and >potentially add a comment to explain it better rather than shoot a patch >rightaway. > Your are right. I am really willing to understand why we want to use this mechanisum. So the correct procedure is to send a mail to the mail list to query the reason?
