On Thu, Oct 18, 2018 at 06:30:39PM +0200, Michal Hocko wrote: >On Thu 18-10-18 14:10:08, Wei Yang wrote: >> 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. > >I am happy to hear that. > >> So the correct procedure is to send a mail to the mail list to query the >> reason? > >It is certainly better to ask a question than send a patch without a >proper justification. I would also encourage to use git blame to see >which patch has introduced the specific piece of code. Many times it >helps to understand the motivation. I would also encourage to go back to >the mailing list archives and the associate discussion to the specific >patch. In many cases there is Link: tag which can help you to find the >respective discussion. > Sure, thanks for your suggestion. >Thanks! > >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me
