The x86 CPUID information is also wrong on this machine. All 4 cores report the same "APIC id" (sort of hardware core ID), I guess all your 4 cores are virtualized over a single hardware core and the hypervisor doesn't care about emulating topology information correctly.
Brice Le 02/08/2023 à 15:23, Max R. Dechantsreiter a écrit :
Hi Brice, Well, the VPS gives me a 4-core slice of an Intel(R) Xeon(R) CPU E5-2620 node, which is Sandy Bridge EP, with 6 physical cores, so probably 12 cores on the node. The numbering does seem wacky: it seems to describe a node with 2 8-core CPUs. This is the VPS on which I host my Web site; I use its shell account for sundry testing, mostly of build procedures. Is there anything I could do to get hwloc to work? Regards, Max --- On Wed, Aug 02, 2023 at 03:12:27PM +0200, Brice Goglin wrote:Hello There's something wrong in this machine. It exposes 4 cores (number 0 to 3) and no NUMA node, but says the only allowed resources are cores 8-15,24-31 and NUMA node 1. That's why hwloc says the topology is empty (running lstopo --disallowed shows NUMA 0 and cores 0-3 in red, which means they aren't allowed). How did this get configured so badly? Brice Le 02/08/2023 à 14:54, Max R. Dechantsreiter a écrit :Hello, On my VPS I tested my build of hwloc-2.9.2 by running lstopo: ./lstopo hwloc: Topology became empty, aborting! Segmentation fault On a GCP n1-standard-2 a similar build (GCC 12.2 vs. 13.2) seemed to work: ./lstopo hwloc/nvml: Failed to initialize with nvmlInit(): Driver Not Loaded Machine (7430MB total) Package L#0 NUMANode L#0 (P#0 7430MB) L3 L#0 (45MB) + L2 L#0 (256KB) + L1d L#0 (32KB) + L1i L#0 (32KB) + Core L#0 PU L#0 (P#0) PU L#1 (P#1) HostBridge PCI 00:03.0 (Other) Block(Disk) "sda" PCI 00:04.0 (Ethernet) Net "ens4" PCI 00:05.0 (Other) (from which I conclude my build procedure is correct). At the suggestion of Brice Goglin (in response to my post of the same issue to Open MPI Users), I rebuilt with '--enable-debug' and ran lstopo; then I also ran hwloc-gather-topology hwloc-gather-topology The resulting lstopo.tar.gz and hwloc-gather-topology.tar.gz are attached, as I was unable to recognize the underlying problem, although I believe it could be a system issue, for my builds of OpenMPI on the VPS used to work before a new OS image was installed. Max
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