diff --git a/nixos/modules/services/continuous-integration/hercules-ci-agent/common.nix b/nixos/modules/services/continuous-integration/hercules-ci-agent/common.nix index 9f9b86ee61c..c6f743a71d4 100644 --- a/nixos/modules/services/continuous-integration/hercules-ci-agent/common.nix +++ b/nixos/modules/services/continuous-integration/hercules-ci-agent/common.nix @@ -37,15 +37,22 @@ let description = '' Number of tasks to perform simultaneously. - A task is a single derivation build or an evaluation. + A task is a single derivation build, an evaluation or an effect run. At minimum, you need 2 concurrent tasks for x86_64-linux in your cluster, to allow for import from derivation. concurrentTasks can be around the CPU core count or lower if memory is the bottleneck. + + The optimal value depends on the resource consumption characteristics of your workload, + including memory usage and in-task parallelism. This is typically determined empirically. + + When scaling, it is generally better to have a double-size machine than two machines, + because each split of resources causes inefficiencies; particularly with regards + to build latency because of extra downloads. ''; - type = types.int; - default = 4; + type = types.either types.ints.positive (types.enum [ "auto" ]); + default = "auto"; }; workDirectory = mkOption { description = ''