Matthew Wilcox <willy@xxxxxxxxxxxxx> writes: > On Mon, Dec 18, 2017 at 01:35:47PM -0700, Ross Zwisler wrote: >> What I'm hoping to do with this series is to just provide a sysfs >> representation of the HMAT so that applications can know which NUMA nodes to >> select with existing utilities like numactl. This series does not currently >> alter any kernel behavior, it only provides a sysfs interface. >> >> Say for example you had a system with some high bandwidth memory (HBM), and >> you wanted to use it for a specific application. You could use the sysfs >> representation of the HMAT to figure out which memory target held your HBM. >> You could do this by looking at the local bandwidth values for the various >> memory targets, so: >> >> # grep . /sys/devices/system/hmat/mem_tgt*/local_init/write_bw_MBps >> /sys/devices/system/hmat/mem_tgt2/local_init/write_bw_MBps:81920 >> /sys/devices/system/hmat/mem_tgt3/local_init/write_bw_MBps:40960 >> /sys/devices/system/hmat/mem_tgt4/local_init/write_bw_MBps:40960 >> /sys/devices/system/hmat/mem_tgt5/local_init/write_bw_MBps:40960 >> >> and look for the one that corresponds to your HBM speed. (These numbers are >> made up, but you get the idea.) > > Presumably ACPI-based platforms will not be the only ones who have the > ability to expose different bandwidth memories in the future. I think > we need a platform-agnostic way ... right, PowerPC people? Yes! I don't have any detail at hand but will try and rustle something up. cheers -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
