slv-smt-disable

# 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 ```bash 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 ```bash # on the host cat /proc/cmdline # should contain nosmt=force lscpu | grep -E 'Thread|Core|Socket' # Thread(s) per core: 1 ``` ## Rollback ```bash sudo sed -i 's/ nosmt=force//' /etc/default/grub sudo update-grub sudo rm /var/lib/slv/.smt_disabled sudo reboot ```