Hello Assuming the NUMA distance matrix is available, the distance between a CPU and a PCI device is basically the distance between the NUMA node that contains this CPU and the NUMA node close to the PCI device.
In theory, you would have 1) CPU to local NUMA node = constant 2) NUMA node to other NUMA node = the significant part when looking at I/O affinity 3) other NUMA node to local PCI device = constant when you switch between CPUs, and pretty-much constant when you switch between PCI devices Keep in mind that (2) is a "relative latency", not an actual physical distance, but it's enough for "comparing distances". Brice Le 09/01/2015 10:30, Pradeep Kiruvale a écrit : > Hi Brice, > > Thanks for the reply. Is it possible to get the distance matrix for > each cpu and the pci device from these hwloc apis? > > Regards, > Pradeep > > On 8 January 2015 at 18:39, Brice Goglin <brice.gog...@inria.fr > <mailto:brice.gog...@inria.fr>> wrote: > > Hello, > > hwloc_topology_init(&topology); > hwloc_topology_set_flags(topology, HWLOC_TOPOLOGY_FLAG_IO_DEVICES); > hwloc_topology_load(topology); > > Then you can use hwloc_get_next_pcidev() to iterate over the > entire list PCI devices. If you want to know whether it's > connected to a specific NUMA node, start from the PCI hwloc_obj_t > and walk up the ->parent pointer until you find a NUMA node object > (not guaranteed, could be connected to something else, even > something that is not a child of a NUMA node, for instance the > entire machine object). > > Otherwise, you can start at the NUMA node object, walk its > children until you find some object of type Bridge, then > recursively walk children to find all PCI objects (it's often > organized as a imbalanced tree, there can other bridges in the > middle). > > Brice > > > > > Le 08/01/2015 17:19, Pradeep Kiruvale a écrit : >> Hi All, >> >> I am looking for a sample application which can provide me the >> list of PCI devices connected >> to each NUMA node. Please let me know how can access the >> information programmatically on >> a Linux system using hwloc APIs. >> >> Regards, >> Pradeep >> >> >> >> >> _______________________________________________ >> hwloc-users mailing list >> hwloc-us...@open-mpi.org <mailto:hwloc-us...@open-mpi.org> >> Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users >> Link to this post: >> http://www.open-mpi.org/community/lists/hwloc-users/2015/01/1145.php > > > _______________________________________________ > hwloc-users mailing list > hwloc-us...@open-mpi.org <mailto:hwloc-us...@open-mpi.org> > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users > Link to this post: > http://www.open-mpi.org/community/lists/hwloc-users/2015/01/1147.php > >
