On 11.05.20 19:47, Srikar Dronamraju wrote: > * David Hildenbrand <david@xxxxxxxxxx> [2020-05-08 15:42:12]: > > Hi David, > > Thanks for the steps to tryout. > >>> >>> #! /bin/bash >>> sudo x86_64-softmmu/qemu-system-x86_64 \ >>> --enable-kvm \ >>> -m 4G,maxmem=20G,slots=2 \ >>> -smp sockets=2,cores=2 \ >>> -numa node,nodeid=0,cpus=0-1,mem=4G -numa node,nodeid=1,cpus=2-3,mem=0G \ >> >> Sorry, this line has to be >> >> -numa node,nodeid=0,cpus=0-3,mem=4G -numa node,nodeid=1,mem=0G \ >> >>> -kernel /home/dhildenb/git/linux/arch/x86_64/boot/bzImage \ >>> -append "console=ttyS0 rd.shell rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0" \ >>> -initrd /boot/initramfs-5.2.8-200.fc30.x86_64.img \ >>> -machine pc,nvdimm \ >>> -nographic \ >>> -nodefaults \ >>> -chardev stdio,id=serial \ >>> -device isa-serial,chardev=serial \ >>> -chardev socket,id=monitor,path=/var/tmp/monitor,server,nowait \ >>> -mon chardev=monitor,mode=readline >>> >>> to get a cpu-less and memory-less node 1. Never tried with node 0. >>> > > I tried > > qemu-system-x86_64 -enable-kvm -m 4G,maxmem=20G,slots=2 -smp sockets=2,cores=2 -cpu host -numa node,nodeid=0,cpus=0-3,mem=4G -numa node,nodeid=1,mem=0G -vga none -nographic -serial mon:stdio /home/srikar/fedora.qcow2 > > and the resulting guest was. > > [root@localhost ~]# numactl -H > available: 1 nodes (0) > node 0 cpus: 0 1 2 3 > node 0 size: 3927 MB > node 0 free: 3316 MB > node distances: > node 0 > 0: 10 > > [root@localhost ~]# lscpu > Architecture: x86_64 > CPU op-mode(s): 32-bit, 64-bit > Byte Order: Little Endian > Address sizes: 40 bits physical, 48 bits virtual > CPU(s): 4 > On-line CPU(s) list: 0-3 > Thread(s) per core: 1 > Core(s) per socket: 2 > Socket(s): 2 > NUMA node(s): 1 > Vendor ID: GenuineIntel > CPU family: 6 > Model: 46 > Model name: Intel(R) Xeon(R) CPU X7560 @ 2.27GHz > Stepping: 6 > CPU MHz: 2260.986 > BogoMIPS: 4521.97 > Virtualization: VT-x > Hypervisor vendor: KVM > Virtualization type: full > L1d cache: 32K > L1i cache: 32K > L2 cache: 4096K > L3 cache: 16384K > NUMA node0 CPU(s): 0-3 > Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni vmx ssse3 cx16 sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer hypervisor lahf_lm cpuid_fault pti ssbd ibrs ibpb tpr_shadow vnmi flexpriority ept vpid tsc_adjust arat umip arch_capabilities > > [root@localhost ~]# cat /sys/devices/system/node/online > 0 > [root@localhost ~]# cat /sys/devices/system/node/possible > 0-1 > > --------------------------------------------------------------------------------- > > I also tried > > qemu-system-x86_64 -enable-kvm -m 4G,maxmem=20G,slots=2 -smp sockets=2,cores=2 -cpu host -numa node,nodeid=1,cpus=0-3,mem=4G -numa node,nodeid=0,mem=0G -vga none -nographic -serial mon:stdio /home/srikar/fedora.qcow2 > > and the resulting guest was. > > [root@localhost ~]# numactl -H > available: 1 nodes (0) > node 0 cpus: 0 1 2 3 > node 0 size: 3927 MB > node 0 free: 3316 MB > node distances: > node 0 > 0: 10 > > [root@localhost ~]# lscpu > Architecture: x86_64 > CPU op-mode(s): 32-bit, 64-bit > Byte Order: Little Endian > Address sizes: 40 bits physical, 48 bits virtual > CPU(s): 4 > On-line CPU(s) list: 0-3 > Thread(s) per core: 1 > Core(s) per socket: 2 > Socket(s): 2 > NUMA node(s): 1 > Vendor ID: GenuineIntel > CPU family: 6 > Model: 46 > Model name: Intel(R) Xeon(R) CPU X7560 @ 2.27GHz > Stepping: 6 > CPU MHz: 2260.986 > BogoMIPS: 4521.97 > Virtualization: VT-x > Hypervisor vendor: KVM > Virtualization type: full > L1d cache: 32K > L1i cache: 32K > L2 cache: 4096K > L3 cache: 16384K > NUMA node0 CPU(s): 0-3 > Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc arch_perfmon rep_good nopl xtopology cpuid tsc_known_freq pni vmx ssse3 cx16 sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer hypervisor lahf_lm cpuid_fault pti ssbd ibrs ibpb tpr_shadow vnmi flexpriority ept vpid tsc_adjust arat umip arch_capabilities > > [root@localhost ~]# cat /sys/devices/system/node/online > 0 > [root@localhost ~]# cat /sys/devices/system/node/possible > 0-1 > > Even without my patch, both the combinations, I am still unable to see a > cpuless, memoryless node being online. And the interesting part being even Yeah, I think on x86, all memory-less and cpu-less nodes are offline as default. Especially when hotunplugging cpus/memory, we set them offline as well. But as Michal mentioned, the node handling code is complicated and differs between various architectures. > if I mark node 0 as cpuless,memoryless and node 1 as actual node, the system > somewhere marks node 0 as the actual node. Is the kernel maybe mapping PXM 1 to node 0 in that case, because it always requires node 0 to be online/contain memory? Would be interesting what happens if you hotplug a DIMM to (QEMU )node 0 - if PXM 0 will be mapped to node 1 then as well. -- Thanks, David / dhildenb
