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. 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]. [1] https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1263745.html > Thanks. > > . >
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