On Wed, Apr 03, 2013 at 12:10:22PM +0200, Michael Kerrisk wrote: > Hello Minchan, > > On Mon, Mar 25, 2013 at 7:21 AM, Minchan Kim <minchan@xxxxxxxxxx> wrote: > > These day, there are many platforms avaiable in the embedded market > > and they are smarter than kernel which has very limited information > > about working set so they want to involve memory management more heavily > > like android's lowmemory killer and ashmem or recent many lowmemory > > notifier(there was several trial for various company NOKIA, SAMSUNG, > > Linaro, Google ChromeOS, Redhat). > > > > One of the simple imagine scenario about userspace's intelligence is that > > platform can manage tasks as forground and backgroud so it would be > > better to reclaim background's task pages for end-user's *responsibility* > > although it has frequent referenced pages. > > > > This patch adds new knob "reclaim under proc/<pid>/" so task manager > > can reclaim any target process anytime, anywhere. It could give another > > method to platform for using memory efficiently. > > > > It can avoid process killing for getting free memory, which was really > > terrible experience because I lost my best score of game I had ever > > after I switch the phone call while I enjoyed the game. > > > > Writing 1 to /proc/pid/reclaim reclaims only file pages. > > Writing 2 to /proc/pid/reclaim reclaims only anonymous pages. > > Writing 3 to /proc/pid/reclaim reclaims all pages from target process. > > This interface seems to work as advertized, at least from some light > testing that I've done. Thanks for the testing! > > However, the interface is a quite blunt instrument. Would there be any > virtue in extending it so that an address range could be written to > /proc/PID/reclaim? Used in conjunction with /proc/PID/maps, a manager > process might then choose to trigger reclaim of just selected regions > of a processes address space. Thus, one might reclaim file backed > pages in a range using: > > echo '2 start-address end-address' > /proc/PID/reclaim > > What do you think? It is really nice idea because some platform use a address space with mulitple object. Simply, multiple application could work in a address space but they use separate virtual address range in a address space. In such model, per-process reclaim isn't vaild any more so your idea would be nice for it. One nitpick is that I'd like to use (address, size) instead of (start_address , end_address) because we always confuse that end_address itself is inclusive or not in the range. And I am thinking another options like this RECLAIM_SOFT_[FILE|ANON] It reclaims pages which are not workset. RECLAIM_HARD_[FILE|ANON] It reclaims pages of range unconditionally although pages are shared by several processes. But before that, I'd like to hear other guys's opinion. > > Thanks, > > Michael > > -- > 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> -- 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>