CentOS/Grub

grub2-mkconfig -o /boot/grub2/grub.cfg

# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Adding boot menu entry for UEFI Firmware Settings ...
done

performance tweaks /etc/default/grub

# vim grub
GRUB_TIMEOUT=60
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"

#GRUB_CMDLINE_LINUX="crashkernel=auto rhgb quiet splash selinux=0"

#GRUB_CMDLINE_LINUX="crashkernel=auto rhgb quiet splash intel_pstate=disable pcie_aspm.policy=performance pci=pcie_b
us_perf noibrs noibpb nopti nospectre_v2 nospectre_v1 l1tf=off nospec_store_bypass_disable no_stf_barrier mds=off mi
tigations=off intel_idle.max_cstate=0 idle=poll transparent_hugepage=never audit=0 selinux=0 nmi_watchdog=0 nohz=on
clocksource=tsc nosoftlockup mce=ignore_ce cpuidle.off=1 skew_tick=1 processor.max_cstate=0 acpi_irq_nobalance"

GRUB_CMDLINE_LINUX="crashkernel=auto rhgb quiet splash intel_pstate=disable pcie_aspm.policy=performance pci=pcie_bu
s_perf noibrs noibpb nopti nospectre_v2 nospectre_v1 l1tf=off nospec_store_bypass_disable no_stf_barrier mds=off mit
igations=off intel_idle.max_cstate=0 idle=poll transparent_hugepage=never audit=0 selinux=0"

GRUB_DISABLE_RECOVERY="true"