From a583a2bc59a4ee2b067e5520f6c5bc0c61852c32 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 7 Aug 2013 11:51:55 +0000 Subject: 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 '' -A system real 0m0.974s user 0m0.875s sys 0m0.088s $ NIX_REMOTE=daemon nix-instantiate '' -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 '' -A system real 0m1.074s user 0m0.809s sys 0m0.098s --- src/libstore/build.cc | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'src/libstore/build.cc') diff --git a/src/libstore/build.cc b/src/libstore/build.cc index 1ca99dcc5c..67e38da0bb 100644 --- a/src/libstore/build.cc +++ b/src/libstore/build.cc @@ -7,6 +7,7 @@ #include "local-store.hh" #include "util.hh" #include "archive.hh" +#include "affinity.hh" #include #include @@ -366,6 +367,8 @@ void Goal::trace(const format & f) /* Common initialisation performed in child processes. */ static void commonChildInit(Pipe & logPipe) { + restoreAffinity(); + /* Put the child in a separate session (and thus a separate process group) so that it has no controlling terminal (meaning that e.g. ssh cannot open /dev/tty) and it doesn't receive @@ -568,6 +571,7 @@ static void runSetuidHelper(const string & command, args.push_back(0); restoreSIGPIPE(); + restoreAffinity(); execve(program.c_str(), (char * *) &args[0], 0); throw SysError(format("executing `%1%'") % program); -- cgit 1.4.1