mirror of
https://github.com/ryan4yin/nix-config.git
synced 2026-08-29 22:37:12 +02:00
Ryan Yin
db953c0504
Compressed writeback cache in front of the disk swapfile keeps cold anon pages in RAM instead of the SSD, freeing page cache for the ~78GB mmap'd LLM weights. zstd's ratio keeps ~5G more anon bytes in the capped pool than lz4 at negligible cost (CPU peaks ~30% on this host); pool capped at 10% so it never competes with the weight cache.
113 lines
3.5 KiB
Nix
113 lines
3.5 KiB
Nix
{
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disko,
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myvars,
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lib,
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pkgs,
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...
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}:
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#############################################################
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#
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# Ai - my main computer, with NixOS + I5-13600KF + RTX 4090 GPU, for gaming & daily use.
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#
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#############################################################
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let
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hostName = "ai"; # Define your hostname.
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inherit (myvars.networking) mainGateway mainGateway6 nameservers;
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inherit (myvars.networking.hostsAddr.${hostName}) iface ipv4 ipv6;
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ipv4WithMask = "${ipv4}/24";
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ipv6WithMask = "${ipv6}/64";
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in
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{
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imports = [
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disko.nixosModules.default
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# disks
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./disko-fs.nix
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./disko-fs-data.nix
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./netdev-mount.nix
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# Include the results of the hardware scan.
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./hardware-configuration.nix
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./hardware-intel.nix
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./hardware-nvidia.nix
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./preservation.nix
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./secureboot.nix
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# others
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./ai
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];
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# Zram consumes physical memory for compression, which can cause a deadlock and system hang if the model size approaches the physical memory limit.
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# Disable the whole module (zram device + its swappiness=180 sysctl tunings); this host uses a disk swapfile instead.
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modules.zram.enable = false;
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# zswap: compressed writeback cache in front of the disk swapfile.
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# Keeps swapped cold anon pages compressed in RAM instead of the SSD, which frees more
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# page cache for the ~78GB mmap'd LLM weights (mmap file pages never go through zswap).
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# Safe here: disk swapfile remains the real backing store, no zram deadlock structure.
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# - zstd: CPU is not the bottleneck here (llama.cpp peaks ~30% util); its ~2.5x ratio
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# keeps ~5G more anon bytes in the capped pool than lz4, and ~5us decompress is noise
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# vs the ~100us SSD fault it avoids.
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# - 10% pool (~9G): the module default 25% (~23G) would compete with the weight cache.
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boot.zswap = {
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enable = true;
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compressor = "zstd";
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maxPoolPercent = 10;
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};
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services.sunshine.enable = false;
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services.tuned.ppdSettings.main.default = lib.mkForce "performance";
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powerManagement.resumeCommands = ''
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# Insta360 Link may stay enumerated with a stalled UVC endpoint after S3 resume.
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${pkgs.coreutils}/bin/sleep 1
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${pkgs.usbutils}/bin/usbreset 2e1a:4c01 || true
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'';
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networking = {
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inherit hostName;
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# we use networkd instead
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networkmanager.enable = false; # provides nmcli/nmtui for wifi adjustment
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useDHCP = false;
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};
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networking.useNetworkd = true;
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systemd.network.enable = true;
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systemd.network.networks."10-${iface}" = {
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matchConfig.Name = [ iface ];
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networkConfig = {
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Address = [
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ipv4WithMask
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ipv6WithMask
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];
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DNS = nameservers;
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DHCP = "ipv6"; # enable DHCPv6 only, so we can get a GUA.
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IPv6AcceptRA = true; # for Stateless IPv6 Autoconfiguraton (SLAAC)
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LinkLocalAddressing = "ipv6";
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};
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routes = [
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{
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Destination = "0.0.0.0/0";
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Gateway = mainGateway;
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}
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{
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Destination = "::/0";
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Gateway = mainGateway6;
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GatewayOnLink = true; # it's a gateway on local link.
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}
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];
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linkConfig.RequiredForOnline = "routable";
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};
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# This value determines the NixOS release from which the default
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# settings for stateful data, like file locations and database versions
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# on your system were taken. It‘s perfectly fine and recommended to leave
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# this value at the release version of the first install of this system.
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# Before changing this value read the documentation for this option
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# (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
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system.stateVersion = "25.11"; # Did you read the comment?
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}
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