On 2018/1/17 5:03, Jerome Glisse wrote: > CAPI (on IBM Power8 and 9) and CCIX are two new standard that > build on top of existing interconnect (like PCIE) and add the > possibility for cache coherent access both way (from CPU to > device memory and from device to main memory). This extend > what we are use to with PCIE (where only device to main memory > can be cache coherent but not CPU to device memory). > Yes, and more than CAPI/CCIX. E.g A SoC may connected with different types of memory through internal system-bus. > How is this memory gonna be expose to the kernel and how the > kernel gonna expose this to user space is the topic i want to > discuss. I believe this is highly device specific for instance > for GPU you want the device memory allocation and usage to be > under the control of the GPU device driver. Maybe other type > of device want different strategy. > > The HMAT patchset is partialy related to all this as it is about > exposing different type of memory available in a system for CPU > (HBM, main memory, ...) and some of their properties (bandwidth, > latency, ...). > Yes, and different type of memory doesn't mean device-memory or Nvdimm only(which are always think not as reliable as DDR). > > We can start by looking at how CAPI and CCIX plan to expose this > to the kernel and try to list some of the type of devices we > expect to see. Discussion can then happen on how to represent this > internaly to the kernel and how to expose this to userspace. > > Note this might also trigger discussion on a NUMA like model or > on extending/replacing it by something more generic. > Agree, for NUMA model the node distance is not enough when a system has different type of memory. Like the HMAT patches mentioned, different bandwidth ,latency, ... > > Peoples (alphabetical order on first name) sorry if i missed > anyone: > "Anshuman Khandual" <khandual@xxxxxxxxxxxxxxxxxx> > "Balbir Singh" <bsingharora@xxxxxxxxx> > "Dan Williams" <dan.j.williams@xxxxxxxxx> > "John Hubbard" <jhubbard@xxxxxxxxxx> > "Jonathan Masters" <jcm@xxxxxxxxxx> > "Ross Zwisler" <ross.zwisler@xxxxxxxxxxxxxxx> > -- 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>
