On Thu, Aug 26, 2010 at 7:06 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > On Thu, 2010-08-26 at 18:29 +0900, Minchan Kim wrote: >> As I said following mail, I said about free space problem. >> Of course, compaction could move anon pages into somewhere. >> What's is somewhere? At last, it's same zone. >> It can prevent fragment problem but not size of free space. >> So I mean it would be better to move it into another zone(ex, HIGHMEM) >> rather than OOM kill. > > Real machines don't have highmem, highmem sucks!! /me runs It's another topic. I agree highmem isn't a gorgeous. But my desktop isn't real machine? Important thing is that we already have a highmem and many guys include you(kmap stacking patch :))try to improve highmem problems. :) > > Does cross zone movement really matter, I though these crappy devices > were mostly used on crappy hardware with very limited memory, so pretty > much everything would be in zone_normal.. no? No. Until now, many embedded devices have used to small memory. In that case, only there is a DMA zone in system. But as I know, mobile phone starts to use big(?) memory like 1G or above sooner or later. So they starts to use HIGHMEM. Otherwise, 2G/2G space configuration. Some embedded device uses many thread model to port easily from RTOS. In that case, they don't have enough address space for application if it uses 2G/2G model. So we should care of HIGHMEM in embedded system from now on. > > But sure, if there's really a need we can look at maybe doing cross zone > movement. > -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>