Don't apply the CPU affinity hack to nix-shell (and other Perl programs)

As discovered by Todd Veldhuizen, the shell started by nix-shell has
its affinity set to a single CPU.  This is because nix-shell connects
to the Nix daemon, which causes the affinity hack to be applied.  So
we turn this off for Perl programs.
This commit is contained in:
Eelco Dolstra 2013-09-06 16:36:56 +02:00
parent 4b83830d0c
commit 936f9d45ba
5 changed files with 11 additions and 7 deletions

View file

@ -20,6 +20,7 @@ void doInit()
if (!store) {
try {
settings.processEnvironment();
settings.lockCPU = false;
store = openStore();
} catch (Error & e) {
croak(e.what());

View file

@ -54,6 +54,7 @@ Settings::Settings()
gcKeepDerivations = true;
autoOptimiseStore = false;
envKeepDerivations = false;
lockCPU = getEnv("NIX_AFFINITY_HACK", "1") == "1";
}

View file

@ -183,6 +183,9 @@ struct Settings {
(to prevent them from being GCed). */
bool envKeepDerivations;
/* Whether to lock the Nix client and worker to the same CPU. */
bool lockCPU;
private:
SettingsMap settings, overrides;

View file

@ -73,7 +73,7 @@ void RemoteStore::openConnection(bool reserveSpace)
writeInt(PROTOCOL_VERSION, to);
if (GET_PROTOCOL_MINOR(daemonVersion) >= 14) {
int cpu = lockToCurrentCPU();
int cpu = settings.lockCPU ? lockToCurrentCPU() : -1;
if (cpu != -1) {
writeInt(1, to);
writeInt(cpu, to);

View file

@ -33,13 +33,12 @@ void setAffinityTo(int cpu)
int lockToCurrentCPU()
{
#if HAVE_SCHED_SETAFFINITY
if (getEnv("NIX_AFFINITY_HACK", "1") == "1") {
int cpu = sched_getcpu();
if (cpu != -1) setAffinityTo(cpu);
return cpu;
}
#endif
int cpu = sched_getcpu();
if (cpu != -1) setAffinityTo(cpu);
return cpu;
#else
return -1;
#endif
}