nix-super/src/libutil/affinity.hh

#pragma once

namespace nix {

void setAffinityTo(int cpu);
int lockToCurrentCPU();
void restoreAffinity();

}
Run the daemon worker on the same CPU as the client On a system with multiple CPUs, running Nix operations through the daemon is significantly slower than "direct" mode: $ NIX_REMOTE= nix-instantiate '<nixos>' -A system real 0m0.974s user 0m0.875s sys 0m0.088s $ NIX_REMOTE=daemon nix-instantiate '<nixos>' -A system real 0m2.118s user 0m1.463s sys 0m0.218s The main reason seems to be that the client and the worker get moved to a different CPU after every call to the worker. This patch adds a hack to lock them to the same CPU. With this, the overhead of going through the daemon is very small: $ NIX_REMOTE=daemon nix-instantiate '<nixos>' -A system real 0m1.074s user 0m0.809s sys 0m0.098s 2013-08-07 14:51:55 +03:00			`#pragma once`

			`namespace nix {`

			`void setAffinityTo(int cpu);`
			`int lockToCurrentCPU();`
			`void restoreAffinity();`

			`}`