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authorEelco Dolstra <eelco.dolstra@logicblox.com>2013-09-06T14·36+0200
committerEelco Dolstra <eelco.dolstra@logicblox.com>2013-09-06T14·36+0200
commit936f9d45baf474358346666ed9ad7f56960bb455 (patch)
treed6c91635fee9b27da7875b1b6e9052c04b20b072
parent4b83830d0c742b69b59c698a42948eaa6d214c1d (diff)
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.
-rw-r--r--perl/lib/Nix/Store.xs1
-rw-r--r--src/libstore/globals.cc1
-rw-r--r--src/libstore/globals.hh3
-rw-r--r--src/libstore/remote-store.cc2
-rw-r--r--src/libutil/affinity.cc11
5 files changed, 11 insertions, 7 deletions
diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index 8154bcbb0f4b..c449ed5241e8 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -20,6 +20,7 @@ void doInit()
     if (!store) {
         try {
             settings.processEnvironment();
+            settings.lockCPU = false;
             store = openStore();
         } catch (Error & e) {
             croak(e.what());
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index aeb52e1a8696..7e0157cd365a 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -54,6 +54,7 @@ Settings::Settings()
     gcKeepDerivations = true;
     autoOptimiseStore = false;
     envKeepDerivations = false;
+    lockCPU = getEnv("NIX_AFFINITY_HACK", "1") == "1";
 }
 
 
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 50b61725c742..cbc6d4e9848e 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -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;
 
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 3764b4813a4e..3017254baf3b 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -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);
diff --git a/src/libutil/affinity.cc b/src/libutil/affinity.cc
index 7a6310cadb00..3e21f43a2e9d 100644
--- a/src/libutil/affinity.cc
+++ b/src/libutil/affinity.cc
@@ -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
 }