On Thu, May 30, 2019 at 12:51:03PM +0100, Morten Rasmussen wrote: > On Wed, May 29, 2019 at 07:39:17PM -0400, Andrew F. Davis wrote: > > On 5/29/19 5:13 PM, Atish Patra wrote: > > >From: Sudeep Holla <sudeep.holla@xxxxxxx> > > > > > >The current ARM DT topology description provides the operating system > > >with a topological view of the system that is based on leaf nodes > > >representing either cores or threads (in an SMT system) and a > > >hierarchical set of cluster nodes that creates a hierarchical topology > > >view of how those cores and threads are grouped. > > > > > >However this hierarchical representation of clusters does not allow to > > >describe what topology level actually represents the physical package or > > >the socket boundary, which is a key piece of information to be used by > > >an operating system to optimize resource allocation and scheduling. > > > > > > > Are physical package descriptions really needed? What does "socket" imply > > that a higher layer "cluster" node grouping does not? It doesn't imply a > > different NUMA distance and the definition of "socket" is already not well > > defined, is a dual chiplet processor not just a fancy dual "socket" or are > > dual "sockets" on a server board "slotket" card, will we need new names for > > those too.. > > Socket (or package) just implies what you suggest, a grouping of CPUs > based on the physical socket (or package). Some resources might be > associated with packages and more importantly socket information is > exposed to user-space. At the moment clusters are being exposed to > user-space as sockets which is less than ideal for some topologies. Please point out a 32-bit ARM system that has multiple "socket"s. As far as I'm aware, all 32-bit systems do not have socketed CPUs (modern ARM CPUs are part of a larger SoC), and the CPUs are always in one package. Even the test systems I've seen do not have socketed CPUs. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
