nixos/zram: add writebackDevice option and corresponding test

This commit is contained in:
Nick Cao 2023-03-20 22:50:11 +08:00
parent d586805a5c
commit cd3ffbdfe6
No known key found for this signature in database
2 changed files with 46 additions and 8 deletions

View file

@ -82,12 +82,30 @@ in
{command}`cat /sys/class/block/zram*/comp_algorithm`
'';
};
writebackDevice = lib.mkOption {
default = null;
example = "/dev/zvol/tarta-zoot/swap-writeback";
type = lib.types.nullOr lib.types.path;
description = lib.mdDoc ''
Write incompressible pages to this device,
as there's no gain from keeping them in RAM.
'';
};
};
};
config = lib.mkIf cfg.enable {
assertions = [
{
assertion = cfg.writebackDevice == null || cfg.swapDevices <= 1;
message = "A single writeback device cannot be shared among multiple zram devices";
}
];
system.requiredKernelConfig = with config.lib.kernelConfig; [
(isModule "ZRAM")
];
@ -112,6 +130,8 @@ in
zram-size = if cfg.memoryMax != null then "min(${size}, ${toString cfg.memoryMax} / 1024 / 1024)" else size;
compression-algorithm = cfg.algorithm;
swap-priority = cfg.priority;
} // lib.optionalAttrs (cfg.writebackDevice != null) {
writeback-device = cfg.writebackDevice;
};
})
devices));

View file

@ -1,18 +1,36 @@
import ./make-test-python.nix {
name = "zram-generator";
nodes.machine = { ... }: {
zramSwap = {
enable = true;
priority = 10;
algorithm = "lz4";
swapDevices = 2;
memoryPercent = 30;
memoryMax = 10 * 1024 * 1024;
nodes = {
single = { ... }: {
virtualisation = {
emptyDiskImages = [ 512 ];
};
zramSwap = {
enable = true;
priority = 10;
algorithm = "lz4";
swapDevices = 1;
memoryPercent = 30;
memoryMax = 10 * 1024 * 1024;
writebackDevice = "/dev/vdb";
};
};
machine = { ... }: {
zramSwap = {
enable = true;
priority = 10;
algorithm = "lz4";
swapDevices = 2;
memoryPercent = 30;
memoryMax = 10 * 1024 * 1024;
};
};
};
testScript = ''
single.wait_for_unit("systemd-zram-setup@zram0.service")
machine.wait_for_unit("systemd-zram-setup@zram0.service")
machine.wait_for_unit("systemd-zram-setup@zram1.service")
zram = machine.succeed("zramctl --noheadings --raw")