#!/bin/bash


MEMORY=32768
SSDADDRESS=0000:04:00.0

## Calculate number of hugepages to allocate from memory (in MB)
HUGEPAGES="$(($MEMORY/$(($(grep Hugepagesize /proc/meminfo | awk '{print $2}')/1024))))"
## Node to allocate on (node1 for this VM)
NODESPATH=/sys/devices/system/node/node1

# BIND SSD
echo $SSDADDRESS > /sys/bus/pci/devices/$SSDADDRESS/driver/unbind
echo $SSDADDRESS > /sys/bus/pci/drivers/vfio-pci/bind

echo "Allocating hugepages..."
echo $HUGEPAGES > $NODESPATH/hugepages/hugepages-2048kB/nr_hugepages
ALLOC_PAGES=$(cat $NODESPATH/hugepages/hugepages-2048kB/nr_hugepages)

TRIES=0
while (( $ALLOC_PAGES != $HUGEPAGES && $TRIES < 10000 ))
do
    echo 1 > /proc/sys/vm/compact_memory            ## defrag ram
    echo $HUGEPAGES > $NODESPATH/hugepages/hugepages-2048kB/nr_hugepages
    ALLOC_PAGES=$(cat $NODESPATH/hugepages/hugepages-2048kB/nr_hugepages)
    echo "Succesfully allocated $ALLOC_PAGES / $HUGEPAGES"
    let TRIES+=1
done

if [ "$ALLOC_PAGES" -ne "$HUGEPAGES" ]
then
    echo "Not able to allocate all hugepages. Reverting..."
    echo 0 > $NODESPATH/hugepages/hugepages-2048kB/nr_hugepages
    exit 1
fi

# libvirt likes to create a cpuset called "machine" and leave it behind after closing
# this confuses cset. remove it just in case
rmdir /sys/fs/cgroup/cpuset/machine

# reserve cpu 0,4 (core 0) for the host and give 1-3,5-7 (core 1-3) to the guest/vm
cset shield --kthread on --cpu 14-27,42-55

# cset reserves the cpusets for exclusive use but libvirt also wants to create
# new cpusets containing the same cpus. Remove the exclusive flag.
echo 0 > /sys/fs/cgroup/cpuset/system/cpuset.cpu_exclusive
echo 0 > /sys/fs/cgroup/cpuset/user/cpuset.cpu_exclusive

# The kernel's dirty page writeback mechanism uses kthread workers. They introduce
# massive arbitrary latencies when doing disk writes on the host and aren't
# migrated by cset. Restrict the workqueue to use only cpu 0.

echo 1 > /sys/devices/virtual/workqueue/cpumask