message: Add device_timer to Cuda utils
diff: namespace rajaperf
  {
  +/*!
  + * \brief Device timer, returns a time in ns from an arbitrary starting point.
  + * Note that this time is consistent across the whole device.
  + */
  +__device__ __forceinline__ unsigned long long device_timer()
  +{
  + unsigned long long global_timer = 0;
  +#if __CUDA_ARCH__ >= 300
  + asm volatile ("mov.u64 %0, %globaltimer;" : "=l"(global_timer));
  +#endif
  + return global_timer;
  +}
  +
  /*!
  * \brief Simple forall cuda kernel that runs a lambda.
  */
  