On Fri, Sep 8, 2017 at 1:43 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Thu, Sep 7, 2017 at 6:59 PM, Bob Liu <liubo95@xxxxxxxxxx> wrote: >> On 2017/9/8 1:27, Jerome Glisse wrote: > [..] >>> No this are 2 orthogonal thing, they do not conflict with each others quite >>> the contrary. HMM (the CDM part is no different) is a set of helpers, see >>> it as a toolbox, for device driver. >>> >>> HMAT is a way for firmware to report memory resources with more informations >>> that just range of physical address. HMAT is specific to platform that rely >>> on ACPI. HMAT does not provide any helpers to manage these memory. >>> >>> So a device driver can get informations about device memory from HMAT and then >>> use HMM to help in managing and using this memory. >>> >> >> Yes, but as Balbir mentioned requires : >> 1. Don't online the memory as a NUMA node >> 2. Use the HMM-CDM API's to map the memory to ZONE DEVICE via the driver >> >> And I'm not sure whether Intel going to use this HMM-CDM based method for their "target domain" memory ? >> Or they prefer to NUMA approach? Ross？ Dan? > > The starting / strawman proposal for performance differentiated memory > ranges is to get platform firmware to mark them reserved by default. > Then, after we parse the HMAT, make them available via the device-dax > mechanism so that applications that need 100% guaranteed access to > these potentially high-value / limited-capacity ranges can be sure to > get them by default, i.e. before any random kernel objects are placed > in them. Otherwise, if there are no dedicated users for the memory > ranges via device-dax, or they don't need the total capacity, we want > to hotplug that memory into the general purpose memory allocator with > a numa node number so typical numactl and memory-management flows are > enabled. > > Ideally this would not be specific to HMAT and any agent that knows > differentiated performance characteristics of a memory range could use > this scheme. @Dan/Ross With this approach, in a SVM environment, if you would want a PRI(page grant) request to get satisfied from this HMAT-indexed memory node, then do you think we could make that happen. If yes, is that something you guys are currently working on. Chetan -- 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
