Hello Simon, On Sun, Apr 07, 2013 at 03:26:12PM +0800, Simon Jeons wrote: > Ping Minchan. > On 04/02/2013 09:40 PM, Simon Jeons wrote: > >Hi Hugh, > >On 03/28/2013 05:41 AM, Hugh Dickins wrote: > >>On Wed, 27 Mar 2013, Minchan Kim wrote: > >> > >>>Swap subsystem does lazy swap slot free with expecting the page > >>>would be swapped out again so we can't avoid unnecessary write. > >> so we can avoid unnecessary write. > > > >If page can be swap out again, which codes can avoid unnecessary > >write? Could you point out to me? Thanks in advance. ;-) Look at shrink_page_list. 1) PageAnon(page) && !PageSwapCache() 2) add_to_swap's SetPageDirty 3) __remove_mapping P.S) It seems you are misunderstanding. Here isn't proper place to ask a question for your understanding the code. As I know, there are some project(ex, kernelnewbies) and books for study and sharing the knowledge linux kernel. I recommend Mel's "Understand the Linux Virtual Memory Manager". It's rather outdated but will be very helpful to understand VM of linux kernel. You can get it freely but I hope you pay for. So if author become a billionaire by selecting best book in Amazon, he might print out second edition which covers all of new VM features and may solve all of you curiosity. It would be a another method to contribute open source project. :) I believe you talented developers can catch it up with reading the code enoughly and find more bonus knowledge. I think it's why our senior developers yell out RTFM and I follow them. Cheers! -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>