2.4.2-1

Add tree algorithms for allreduce to improve performance at scale.
Add ncclCommAbort() and ncclCommGetAsyncError() to properly handle
network errors and be permit recover.
Detect initial CPU affinity and no longer escape it.

src/include/debug.h

@@ -25,6 +25,7 @@ extern uint64_t ncclDebugMask;
 extern pthread_mutex_t ncclDebugOutputLock;
 extern FILE *ncclDebugFile;
 extern ncclResult_t getHostName(char* hostname, int maxlen);
+extern ncclResult_t getNvmlDevice(int cudaDev, int *nvmlDev);
 
 extern void ncclDebugLog(ncclDebugLogLevel level, unsigned long flags, const char *filefunc, int line, const char *fmt, ...);