opendev/system-config
Code Issues Proposed changes

Use swapfile if no extra device is present

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We are booting instances outside of rax and they don't always come with
extra devices that can be repurposed for swap. If in that case then
create a swapfile instead.

Note we do not use fallocate as swapon's manpage says this is suboptimal
with the linux kernel's swap implementation.

Change-Id: I8b9ce18c18e4069aba7de27bb6a9927627b15b49
This commit is contained in:
Clark Boylan 2019-07-16 09:07:30 -07:00
parent 4e050d981e
commit 319c9c44f0
1 changed files with 16 additions and 5 deletions
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21
make_swap.sh
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@ -21,13 +21,14 @@ if [ `grep SwapTotal /proc/meminfo | awk '{ print $2; }'` -eq 0 ]; then
elif [ -b /dev/xvde ]; then
DEV='/dev/xvde'
fi
SWAPFILE=/swapfile
MEMKB=`grep MemTotal /proc/meminfo | awk '{print $2; }'`
# Use the nearest power of two in MB as the swap size.
# This ensures that the partitions below are aligned properly.
MEM=`python3 -c "import math ; print(2**int(round(math.log($MEMKB/1024, 2))))"`
# Avoid using config drive device for swap
if [ -n "$DEV" ] && ! blkid | grep $DEV | grep TYPE ; then
MEMKB=`grep MemTotal /proc/meminfo | awk '{print $2; }'`
# Use the nearest power of two in MB as the swap size.
# This ensures that the partitions below are aligned properly.
MEM=`python3 -c "import math ; print(2**int(round(math.log($MEMKB/1024, 2))))"`
if mount | grep ${DEV} > /dev/null; then
echo "*** ${DEV} appears to already be mounted"
echo "*** ${DEV} unmounting and reformating"
@ -61,6 +62,16 @@ if [ `grep SwapTotal /proc/meminfo | awk '{ print $2; }'` -eq 0 ]; then
perl -nle "m,${DEV}, || print" -i /etc/fstab
echo "${DEV}1 none swap sw 0 0" >> /etc/fstab
echo "${DEV}2 /opt ext4 errors=remount-ro,barrier=0 0 2" >> /etc/fstab
mount -a
elif [ ! -f "$SWAPFILE" ] ; then
# We don't have real devices to use so we make a swap file instead.
# Note you can skip this by precreating /swapfile.
# bs here is 1Mb
sudo dd if=/dev/zero of=${SWAPFILE} bs=1048576 count=${MEM}
sudo chown root:root $SWAPFILE
sudo chmod 600 $SWAPFILE
sudo mkswap $SWAPFILE
echo "${SWAPFILE} none swap sw 0 0" >> /etc/fstab
fi
swapon -a
mount -a
fi