On 09/09/2014 09:16 AM, Boaz Harrosh wrote: > On 08/22/2014 05:36 PM, Dave Hansen wrote: >> Is there a reason you don't just do this at boot and have to use hotplug >> at runtime for it? > > This is a plug and play thing. This memory region is not reached via memory > controller, it is on the ACPI/SBUS device with physical address/size specified > there. On load of block-device this will be called. Also a block device can > be unloaded and should be able to cleanup. OK, cool. >> What are the ratio of pmem to RAM? Is it possible >> to exhaust all of RAM with 'struct page's for pmem? > > Yes! in the not very distant future there will be systems that have only pmem. > yes no RAM. This is because once available some pmem has much better power > efficiency then DRAM, because of the no refresh thing. So even cellphones and > embedded system first. ... > So the Admin/setup will need to calculate and configure the proper ratio of > volatile vs non-volatile portions of its system for proper usage. I'm just worried that somebody will plug a card in, and immediately OOM the system. Or, even worse, a card gets plugged in and 98% of the RAM gets used by this prd driver and the kernel performs horribly. I think we probably need to have some tracking of how much memory is getting used for these mem_map[]s, and make sure they don't get out of hand. -- 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>