e2e: enforce virtual machine cache topology levels#716
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This does not seem to be enough, problem persists (and gets even worse, see L3...) at least on one host system: --> keeping the PR as Draft. |
klihub
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Jul 27, 2026
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| def qemuopts(numalist): | ||
| machineparam = "-machine q35,kernel-irqchip=split" | ||
| cpuparam = "-cpu host,x2apic=on" |
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I think this quite recent blog post suggests that in some cases we'd need the -machine q35,accel=kvm,kernel-irqchip=split -cpu host,+topoext with the +topoext cpu option explicitly given if -cpu host is also used.
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With that extra option in place I get
[root@n4c16-fedora-43-containerd ~]# grep . /sys/devices/system/cpu/cpu0/cache/index*/*_list
/sys/devices/system/cpu/cpu0/cache/index0/shared_cpu_list:0-1
/sys/devices/system/cpu/cpu0/cache/index1/shared_cpu_list:0-1
/sys/devices/system/cpu/cpu0/cache/index2/shared_cpu_list:0-1
/sys/devices/system/cpu/cpu0/cache/index3/shared_cpu_list:0-7
[root@n4c16-fedora-43-containerd ~]# grep . /sys/devices/system/cpu/cpu0/topology/{thread_siblings_list,package_cpus_list}
/sys/devices/system/cpu/cpu0/topology/thread_siblings_list:0-1
/sys/devices/system/cpu/cpu0/topology/package_cpus_list:0-7
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@askervin: Can you test the updated PR on the host where you saw the failure earlier ?
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On some host platforms, Qemu reports every virtual machine CPU hyperthread having its own L1d, L1i and L2 caches. Force virtual CPU cache topology where these caches are shared between thread siblings. Signed-off-by: Antti Kervinen <antti.kervinen@intel.com>
Signed-off-by: Krisztian Litkey <krisztian.litkey@intel.com>
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On some host platforms, Qemu reports every virtual machine CPU hyperthread having its own L1d, L1i and L2 caches. Force virtual CPU cache topology where these caches are shared between thread siblings.