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System

2 socket system with AMD EPYC 7453 28-Core processors with HT enabled, 256 gigabytes of RAM.

The baseline kernel (a) is 6.3-rc4 with the configuration very close to openSUSE Leap 15.3.
The modified kernel (b) is 6.3-rc4 with __GFP_UNMAPPED patches applied.

Background load

#!/bin/bash

D_DIR=/lib/modules/$(uname -r)/kernel/net/netfilter
KERNEL_MODULES=$(ls -1 $KMOD_DIR | sed 's/.ko$//')

function modules_load() {
        for m in $KERNEL_MODULES; do
                modprobe $m &> /dev/null
        done
}

function modules_unload() {
        for m in $KERNEL_MODULES; do
                modprobe -r $m &> /dev/null
        done
}

while :; do
        echo time: `date +%s`
        modules_unload
        modules_load
done