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linux_wiki:use_proc_sys_and_sysctl_to_modify_and_set_kernel_runtime_parameters [2016/09/18 16:52] billdozor [Tuned] |
linux_wiki:use_proc_sys_and_sysctl_to_modify_and_set_kernel_runtime_parameters [2019/05/25 23:50] (current) |
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| Modifying runtime or persistent kernel parameters. | Modifying runtime or persistent kernel parameters. | ||
| + | |||
| + | ---- | ||
| + | |||
| + | ====== Lab Setup ====== | ||
| + | |||
| + | The following virtual machines will be used: | ||
| + | * server1.example.com (192.168.1.150) -> Configure the kernel parameters here | ||
| + | |||
| + | ---- | ||
| + | |||
| + | ====== Help ====== | ||
| + | |||
| + | Finding help in this section. | ||
| + | * Sysctl man page< | ||
| ---- | ---- | ||
| Line 28: | Line 42: | ||
| sysctl -w vm.swappiness=10 | sysctl -w vm.swappiness=10 | ||
| sysctl vm.swappiness | sysctl vm.swappiness | ||
| + | |||
| + | # Or | ||
| + | sysctl -a | grep swappiness | ||
| </ | </ | ||
| * -w -> write | * -w -> write | ||
| Line 44: | Line 61: | ||
| * Default system values: / | * Default system values: / | ||
| - | * Persistent configuration over rides: / | + | * Persistent configuration over rides: /etc/sysctl.d/filename.conf |
| \\ | \\ | ||
| - | Create entries in / | + | Create entries in /etc/sysctl.d/ |
| <code bash> | <code bash> | ||
| vim / | vim / | ||
| Line 57: | Line 74: | ||
| Load settings from a file | Load settings from a file | ||
| <code bash> | <code bash> | ||
| - | sysctl -p < | + | sysctl -p / |
| </ | </ | ||
| * If no file name is specified, defaults to: / | * If no file name is specified, defaults to: / | ||
| + | |||
| + | \\ | ||
| + | Load all settings | ||
| + | <code bash> | ||
| + | sysctl --system | ||
| + | </ | ||
| ===== Tuned ===== | ===== Tuned ===== | ||
| Line 65: | Line 88: | ||
| Tuned is a " | Tuned is a " | ||
| - | Starting in EL 7.2, some parameters (such as vm.swappiness) are set AFTER systemd-sysctl.service by the tuned service. | + | * **Notes** |
| + | * Starting in EL 7.2, some parameters (such as vm.swappiness) are set AFTER systemd-sysctl.service by the tuned service. | ||
| + | * In EL 7.4, it appears that tuned defaults to honor sysctl (/ | ||
| + | # Whether to reapply sysctl from the e.g / | ||
| + | # If enabled these sysctls will be re-appliead after Tuned sysctls are | ||
| + | # applied, i.e. Tuned sysctls will not override system sysctls. | ||
| + | reapply_sysctl = 1 | ||
| + | ....SNIP....</ | ||
| + | * Either way; be aware of tuned and its potential to conflict with sysctl. | ||
| \\ | \\ | ||