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2 Commits
Author SHA1 Message Date
Ilker ManapandClaude Opus 5 634f87ba15 Provision nodes with the host CPU model
CI / test (push) Successful in 1m26s
Proxmox defaults a VM to kvm64, which hides AVX, AVX2, FMA and even SSE4.2
from the guest. llama.cpp then loads libggml-cpu-x64.so — its scalar
baseline — instead of the backend built for the host's instruction set, and
an inference node is not slightly slower but unusable.

Measured on node05, an 8-core VM on a Xeon E5-2680 v4, same weights, same
thread count, the only change being --cpu host:

  Qwen2.5-Coder     kvm64   host
  1.5B q4_K_M        5.80  39.09  tok/s
  3B   q4_K_M        2.90  20.51
  7B   q4_K_M        1.33   9.88

Prompt processing went from 7.6 to 143.8, a factor of nineteen.

This cost an afternoon because nothing looks broken. The node registers, the
engine starts, the replies are correct; every number is just small, and the
conclusion that suggests itself is that CPU inference is hopeless rather
than that the VM cannot multiply efficiently. A 14B model at 1.7 tokens a
second was nearly written off on that basis.

The trade is live migration, which a VM pinned to the host CPU cannot do.
For a node whose job is arithmetic that is the right way round, and --cpu
overrides it where it is not.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-16 20:42:48 +02:00
Ilker ManapandClaude Opus 5 aa4da3264d Make adding a node one command, and check the engine actually runs
CI / test (push) Successful in 1m26s
Building node05 by hand turned up three things worth fixing, in the order
they bit.

Onboarding died on "Host key verification failed" — an error about ssh, in
the middle of a script whose entire job is to talk to a machine created
sixty seconds ago. It now uses accept-new, which learns an unknown host key
and still refuses a changed one; the risk being guarded against is a
substituted machine, not a new one.

Then ssh started refusing connections on a node that had answered a moment
before: cloud-init regenerates the host keys and restarts sshd partway
through a new machine's first minute. The agent was registered and healthy
throughout. Onboarding now waits for ssh rather than failing on it, which
is also what makes running the two halves back to back safe.

Then llama-server: present, executable, and unable to start for want of
libgomp1. The node registered ready and would have stayed ready until a
replica was placed on it and the shard died with a missing shared library
three logs away. The docs already warned about this shape of failure;
nothing checked for it. Onboarding now runs a configured engine and says
plainly when it will not start.

add-node.sh drives both halves. The reason is not keystrokes: the VM name,
the hostname, the node id and the certificate's CN must all be the same
string, and the address appears in three places. Split across two commands
run minutes apart, that agreement is held together by whoever is typing.
Here it is stated once, and the VMID defaults to the last octet of the
address so qm list and ctl nodes stay in the same order. The two halves
remain separately runnable, because needing the hypervisor and needing the
CA really are different access.

Verified by building a throwaway node06 with it: 45 seconds from nothing to
registered, and the engine check caught that node06 had no llama-server.
Destroyed afterwards.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-09-16 19:07:56 +02:00