On 2016/11/8 11:59, Joonsoo Kim wrote: > On Mon, Nov 07, 2016 at 03:46:02PM +0800, Chen Feng wrote: >> >> >> On 2016/11/7 15:44, Chen Feng wrote: >>> On 2016/11/7 15:27, Joonsoo Kim wrote: >>>> On Mon, Nov 07, 2016 at 03:08:49PM +0800, Chen Feng wrote: >>>>> >>>>> >>>>> On 2016/11/7 14:15, Joonsoo Kim wrote: >>>>>> On Tue, Nov 01, 2016 at 03:58:32PM +0800, Chen Feng wrote: >>>>>>> Hello, I hava a question on cma zone. >>>>>>> >>>>>>> When we have cma zone, cma zone will be the highest zone of system. >>>>>>> >>>>>>> In android system, the most memory allocator is ION. Media system will >>>>>>> alloc unmovable memory from it. >>>>>>> >>>>>>> On low memory scene, will the CMA zone always do balance? >>>>>> >>>>>> Allocation request for low zone (normal zone) would not cause CMA zone >>>>>> to be balanced since it isn't helpful. >>>>>> >>>>> Yes. But the cma zone will run out soon. And it always need to do balance. >>>>> >>>>> How about use migrate cma before movable and let cma type to fallback movable. >>>>> >>>>> https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1263745.html >>>> >>>> ZONE_CMA approach will act like as your solution. Could you elaborate >>>> more on the problem of zone approach? >>>> >>> >>> The ZONE approach is that makes cma pages in a zone. It can cause a higher swapin/out >>> than use migrate cma first. > > Interesting result. I should look at it more deeply. Could you explain > me why the ZONE approach causes a higher swapin/out? > The result is that. I don't have a obvious reason. Maybe add a zone, need to do more balance to keep the watermark of cma-zone. cma-zone is always used firstly. Since the test-case alloced the same memory in total. >>> >>> The higher swapin/out may have a performance effect to application. The application may >>> use too much time swapin memory. >>> >>> You can see my tested result attached for detail. And the baseline is result of [1]. >>> >>> >> My test case is run 60 applications and alloc 512MB ION memory. >> >> Repeat this action 50 times > > Could you tell me more detail about your test? > Kernel version? Total Memory? Total CMA Memory? Android system? What > type of memory does ION uses? Other statistics? Etc... Tested on 4.1, android 7, 512MB-cma in 4G memory. ION use normal unmovable memory, I use it to simulate a camera open operator. > > If it tested on the Android, I'm not sure that we need to consider > it's result. Android has a lowmemory killer which is quitely different > with normal reclaim behaviour. Why? > > Thanks. > > > . > -- 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>