161bea9d15
There may be other swap on the device, e.g. swapfile. Setting an explicit high priority value ensures zram is given first preference. Signed-off-By: Sicelo A. Mhlongo <absicsz@gmail.com> Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/9106>
88 lines
2.5 KiB
Bash
88 lines
2.5 KiB
Bash
#!/bin/sh
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# shellcheck disable=SC3043
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set -e
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# shellcheck disable=SC1091
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. /usr/share/misc/source_deviceinfo
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get_mem_size_mb() {
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LC_ALL=C free -m | awk '/^Mem:/{print $2}'
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}
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get_size() {
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# Size defaults to:
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# - 150% of RAM for devices with less than 32GB of RAM
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# - 50% of RAM for devices with greater than 32GB of RAM
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# This is loosely based on some data here:
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# https://gitlab.postmarketos.org/postmarketOS/pmaports/-/issues/4250
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local mem_size_mb size_pct
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mem_size_mb="$(get_mem_size_mb)"
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if [ "$mem_size_mb" -le 32768 ]; then
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size_pct=150
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else
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size_pct=50
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fi
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# Allow overriding the size as a percentage of RAM using a deviceinfo var, or
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# disabling it completely
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if [ -n "$deviceinfo_zram_swap_pct" ]; then
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# 0% --> disable zram swap
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if [ "$deviceinfo_zram_swap_pct" = "0" ]; then
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echo 0
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return
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fi
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size_pct="$deviceinfo_zram_swap_pct"
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fi
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echo $((mem_size_mb * size_pct / 100))
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}
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get_algo() {
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# Default to zstd compression, and allow overriding via deviceinfo
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# TODO: Architecture-specific defaults?
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# TODO: Ensure deviceinfo uses valid and usable algorithm for running
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# kernel
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echo "${deviceinfo_zram_swap_algo:-zstd}"
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}
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set_min_free_kbytes() {
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local mem_size_mb current
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# Set vm.min_free_kbytes to 100000 KB if the kernel's current value
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# is lower. This ensures the kernel starts reclaiming memory early
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# enough to make use of zram swap before the kernel OOM killer fires.
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# This is only applied on devices with >= 1GB of RAM.
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mem_size_mb="$(get_mem_size_mb)"
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[ "$mem_size_mb" -lt 1024 ] && return
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current="$(cat /proc/sys/vm/min_free_kbytes)"
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[ "$current" -ge 100000 ] && return
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sysctl -w vm.min_free_kbytes=100000 >/dev/null
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}
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size=$(get_size)
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algo=$(get_algo)
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[ "$size" -eq 0 ] && exit 0
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if swapon --show=NAME --noheadings | grep -q '^/dev/zram'; then
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echo "ZRAM swap already active, skipping setup"
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exit 0
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fi
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modprobe -q zram num_devices=1
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dev="$(zramctl -f -a "$algo" -s "${size}"M)"
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mkswap "$dev" >/dev/null
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swapon "$dev" -p 300 >/dev/null
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# ZRAM-optimized sysctl settings
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sysctl -w \
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vm.page-cluster=0 \
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vm.swappiness=180 >/dev/null
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set_min_free_kbytes
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echo "ZRAM swap device $dev activated using $algo and size $size MB"
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