On Thu 04-05-17 15:26:55, Balbir Singh wrote: > On Tue, 2017-05-02 at 16:36 +0200, Michal Hocko wrote: > > On Wed 19-04-17 17:52:38, Balbir Singh wrote: [...] > > > 2. kswapd reclaim > > > > How is the memory reclaim handled then? How are users expected to handle > > OOM situation? > > > > 1. The fallback node list for coherent memory includes regular memory > nodes > 2. Direct reclaim works, I've tested it But the direct reclaim would be effective only _after_ all other nodes are full. I thought that kswapd reclaim is a problem because the HW doesn't support aging properly but as the direct reclaim works then what is the actual problem? > > > The reason for exposing this device memory as NUMA is to simplify > > > the programming model, where memory allocation via malloc() or > > > mmap() for example would seamlessly work across both kinds of > > > memory. Since we expect the size of device memory to be smaller > > > than system RAM, we would like to control the allocation of such > > > memory. The proposed mechanism reuses nodemasks and explicit > > > specification of the coherent node in the nodemask for allocation > > > from device memory. This implementation also allows for kernel > > > level allocation via __GFP_THISNODE and existing techniques > > > such as page migration to work. > > > > so it basically resembles isol_cpus except for memory, right. I believe > > scheduler people are more than unhappy about this interface... > > > > isol_cpus were for an era when timer/interrupts and other scheduler > infrastructure present today was not around, but I don't mean to digress. AFAIU, it has been added to _isolate_ some cpus from the scheduling domain and have them available for the explicit affinity usage. You are effectivelly proposing the same thing. -- Michal Hocko SUSE Labs -- 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>
