From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Michael Ellerman Subject: Re: [PATCH v3 0/3] create sysfs representation of ACPI HMAT In-Reply-To: <20171220181937.GB12236@bombadil.infradead.org> References: <20171214021019.13579-1-ross.zwisler@linux.intel.com> <20171214130032.GK16951@dhcp22.suse.cz> <20171218203547.GA2366@linux.intel.com> <20171220181937.GB12236@bombadil.infradead.org> Date: Thu, 21 Dec 2017 23:50:40 +1100 Message-ID: <87mv2cfdnj.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org To: Matthew Wilcox , Ross Zwisler Cc: Michal Hocko , "Box, David E" , Dave Hansen , "Zheng, Lv" , linux-nvdimm@lists.01.org, "Verma, Vishal L" , "Rafael J. Wysocki" , Anaczkowski,, Robert, Lukasz, Erik, Jaroslaw, Marcin, Murugasamy, Artur, Joonas List-ID: Matthew Wilcox 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org