rdmsm4x-changelog-20260926-2120-restore-sysctl-defaults-and-remove-boot-optimizations

Restored macOS kernel sysctl parameters to stock defaults and removed custom boot optimization LaunchDaemons.

Scope

Host: rdmsm4x (macOS 27.2.0, Apple Silicon Mac16,9 M4 Max)
Note: Inventory check confirmed com.user.sysctltuning.plist is also present on rdmbair13m5, rdmbair15m5, and rdmpw3275m. Those hosts currently have active workloads and were not modified during this run; backups were prepared.

Exact Files Touched

Backed up and removed:
- /Library/LaunchDaemons/com.user.sysctltuning.plist
- /Library/LaunchDaemons/limit.maxfiles.plist
Backup destination:
- /Users/richh/dev/fleet/backups/20260926-sysctl-restore/com.user.sysctltuning.plist (SHA256: 90570d47accd0118497b2eb1f555353e23e7551620d9b230ed20a4343f921ae8)
- /Users/richh/dev/fleet/backups/20260926-sysctl-restore/limit.maxfiles.plist (SHA256: 310d9b7baa5d40491a2a3650a6101fce46d9fdd4f0f6b99d916f40df9a88c0a7)

Commands Run

# 1. Reset network sysctl parameters to macOS stock defaults
sudo sysctl -w \
  net.inet.tcp.sendspace=131072 \
  net.inet.tcp.recvspace=131072 \
  net.inet.tcp.autorcvbufmax=4194304 \
  net.inet.tcp.autosndbufmax=4194304 \
  kern.ipc.maxsockbuf=8388608

# 2. Reset filesystem and proc limit sysctl parameters to stock defaults
sudo sysctl -w \
  kern.maxfilesperproc=122880 \
  kern.maxfiles=245760 \
  kern.maxvnodes=263168

# 3. Unload persistent boot LaunchDaemons
sudo launchctl unload /Library/LaunchDaemons/com.user.sysctltuning.plist
sudo launchctl unload /Library/LaunchDaemons/limit.maxfiles.plist

# 4. Backup plists to fleet storage
mkdir -p ~/dev/fleet/backups/20260926-sysctl-restore
sudo cp -p /Library/LaunchDaemons/com.user.sysctltuning.plist ~/dev/fleet/backups/20260926-sysctl-restore/
sudo cp -p /Library/LaunchDaemons/limit.maxfiles.plist ~/dev/fleet/backups/20260926-sysctl-restore/

# 5. Remove custom boot plists
sudo rm /Library/LaunchDaemons/com.user.sysctltuning.plist /Library/LaunchDaemons/limit.maxfiles.plist

Verification Evidence

Sysctl Values Before vs After

Parameter	Custom Tuned	Restored Default	Stock Peer Baseline (`jdmbair13m5`)
`kern.maxvnodes`	`4000000`	`263168`	`263168`
`kern.maxfiles`	`5000000`	`245760`	`245760`
`kern.maxfilesperproc`	`2500000`	`122880`	`122880`
`net.inet.tcp.sendspace`	`1048576`	`131072`	`131072`
`net.inet.tcp.recvspace`	`1048576`	`131072`	`131072`
`net.inet.tcp.autorcvbufmax`	`8388608`	`4194304`	`4194304`
`net.inet.tcp.autosndbufmax`	`8388608`	`4194304`	`4194304`
`kern.ipc.maxsockbuf`	`16777216`	`8388608`	`8388608`

Daemon & Limit Verification

sudo launchctl list | grep -E "sysctl|limit": returned 0 matches (no persistent tuning daemons loaded).
sudo lsof -nP | wc -l: 56,446 open file descriptors (operating well within the 245,760 limit).
/etc/sysctl.conf: verified absent.
nvram boot-args: verified empty.

How to Undo

To re-enable custom optimizations at boot:

sudo cp ~/dev/fleet/backups/20260926-sysctl-restore/com.user.sysctltuning.plist /Library/LaunchDaemons/
sudo cp ~/dev/fleet/backups/20260926-sysctl-restore/limit.maxfiles.plist /Library/LaunchDaemons/
sudo chown root:wheel /Library/LaunchDaemons/com.user.sysctltuning.plist /Library/LaunchDaemons/limit.maxfiles.plist
sudo chmod 644 /Library/LaunchDaemons/com.user.sysctltuning.plist /Library/LaunchDaemons/limit.maxfiles.plist
sudo launchctl load /Library/LaunchDaemons/com.user.sysctltuning.plist
sudo launchctl load /Library/LaunchDaemons/limit.maxfiles.plist

Outstanding Owner Actions

None required for immediate operation.
On next system restart, Darwin will boot cleanly using 100% native kernel limits without any startup overrides.