| name | slv-smt-disable |
| description | Disable SMT (Hyper-Threading) by adding `nosmt=force` to GRUB. Required for stable single-thread performance on Solana validators / RPCs. Reboot required. |
SLV SMT (Hyper-Threading) Disable Skill
Solana validator / RPC throughput is dominated by single-thread instruction performance, so disabling SMT consistently produces higher and more stable performance. Applied during slv v init / slv r init as part of the tuning phase.
How it works
Adds nosmt=force to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub and runs update-grub. After reboot, the kernel only schedules on one logical thread per physical core.
Related ansible playbook
ansible/cmn/smt_disable.yml — appends nosmt=force to GRUB and runs update-grub- Idempotency marker:
/var/lib/slv/.smt_disabled
Standalone run
ansible-playbook -i inventory.yml cmn/smt_disable.yml --limit <host>
Sets need_reboot=true only when GRUB actually changed; the orchestrator reboots when needed.
Verification
cat /proc/cmdline
lscpu | grep -E 'Thread|Core|Socket'
Rollback
sudo sed -i 's/ nosmt=force//' /etc/default/grub
sudo update-grub
sudo rm /var/lib/slv/.smt_disabled
sudo reboot
