Simple, cruddy script to print out some zswap information, and attempt to calculate compression ratio, though unsure if it is accurate, nor if it accounts for overhead. Add -v to get raw dump of the module parameters and kernel debug statistics.

zswap-stats

#! /bin/sh -

ENABLED=$(cat /sys/module/zswap/parameters/enabled)
COMPRESSOR=$(cat /sys/module/zswap/parameters/compressor)
ZPOOL=$(cat /sys/module/zswap/parameters/zpool)
PAGE_SIZE=$(getconf PAGE_SIZE)
STORED_PAGES=$(cat /sys/kernel/debug/zswap/stored_pages)
POOL_TOTAL_SIZE=$(cat /sys/kernel/debug/zswap/pool_total_size)

POOL_SIZE=$(numfmt --to=iec-i $POOL_TOTAL_SIZE)

if [ "$POOL_TOTAL_SIZE" = "0" ]
then
        DECOMPRESSED_SIZE="N/A"
        RATIO="N/A"
else
        DECOMPRESSED_SIZE=$(echo "$STORED_PAGES * $PAGE_SIZE" | bc | numfmt --to=iec-i)
        RATIO=$(echo "scale=3; $STORED_PAGES * $PAGE_SIZE / $POOL_TOTAL_SIZE" | bc -l)
fi

echo "Zswap enabled:            $ENABLED"
echo "Compressor:               $COMPRESSOR"
echo "Zpool:                    $ZPOOL"
echo
echo "Page size:                $PAGE_SIZE"
echo "Stored pages:             $STORED_PAGES"
echo "Pool size:                $POOL_SIZE"
echo "Decompressed size:        $DECOMPRESSED_SIZE"
echo "Page compression ratio:   $RATIO"

if [ "$1" = "-v" ]
then
        echo
        grep -R . /sys/kernel/debug/zswap/
        grep -R . /sys/module/zswap/parameters/
fi