blob: c1748812821e71a86412c6a6566b708ca33244e0 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.zramSwap;
devices = map (nr: "zram${toString nr}") (range 0 (cfg.numDevices - 1));
modprobe = "${pkgs.kmod}/bin/modprobe";
in
{
###### interface
options = {
zramSwap = {
enable = mkOption {
default = false;
type = types.bool;
description = ''
Enable in-memory compressed swap space provided by the zram kernel
module.
See https://www.kernel.org/doc/Documentation/blockdev/zram.txt
'';
};
numDevices = mkOption {
default = 1;
type = types.int;
description = ''
Number of zram swap devices to create.
'';
};
memoryPercent = mkOption {
default = 50;
type = types.int;
description = ''
Maximum amount of memory that can be used by the zram swap devices
(as a percentage of your total memory). Defaults to 1/2 of your total
RAM.
'';
};
priority = mkOption {
default = 5;
type = types.int;
description = ''
Priority of the zram swap devices. It should be a number higher than
the priority of your disk-based swap devices (so that the system will
fill the zram swap devices before falling back to disk swap).
'';
};
};
};
config = mkIf cfg.enable {
system.requiredKernelConfig = with config.lib.kernelConfig; [
(isModule "ZRAM")
];
# Disabling this for the moment, as it would create and mkswap devices twice,
# once in stage 2 boot, and again when the zram-reloader service starts.
# boot.kernelModules = [ "zram" ];
boot.extraModprobeConfig = ''
options zram num_devices=${toString cfg.numDevices}
'';
services.udev.extraRules = ''
KERNEL=="zram[0-9]*", ENV{SYSTEMD_WANTS}="zram-init-%k.service", TAG+="systemd"
'';
systemd.services =
let
createZramInitService = dev:
nameValuePair "zram-init-${dev}" {
description = "Init swap on zram-based device ${dev}";
bindsTo = [ "dev-${dev}.swap" ];
after = [ "dev-${dev}.device" "zram-reloader.service" ];
requires = [ "dev-${dev}.device" "zram-reloader.service" ];
before = [ "dev-${dev}.swap" ];
requiredBy = [ "dev-${dev}.swap" ];
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStop = "${pkgs.runtimeShell} -c 'echo 1 > /sys/class/block/${dev}/reset'";
};
script = ''
set -u
set -o pipefail
# Calculate memory to use for zram
totalmem=$(${pkgs.gnugrep}/bin/grep 'MemTotal: ' /proc/meminfo | ${pkgs.gawk}/bin/awk '{print $2}')
mem=$(((totalmem * ${toString cfg.memoryPercent} / 100 / ${toString cfg.numDevices}) * 1024))
echo $mem > /sys/class/block/${dev}/disksize
${pkgs.utillinux}/sbin/mkswap /dev/${dev}
'';
restartIfChanged = false;
};
in listToAttrs ((map createZramInitService devices) ++ [(nameValuePair "zram-reloader"
{
description = "Reload zram kernel module when number of devices changes";
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
ExecStartPre = "${modprobe} -r zram";
ExecStart = "${modprobe} zram";
ExecStop = "${modprobe} -r zram";
};
restartTriggers = [ cfg.numDevices ];
restartIfChanged = true;
})]);
swapDevices =
let
useZramSwap = dev:
{
device = "/dev/${dev}";
priority = cfg.priority;
};
in map useZramSwap devices;
};
}
|