bfloat16 - Hardware Numerics Definition

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Intel® Deep Learning Boost (Intel® DL Boost) uses bfloat16 format (BF16). This document describes the bfloat16 floating-point format.

BF16 has several advantages over FP16:

  • It can be seen as a short version of FP32, skipping the least significant 16 bits of mantissa.
  • There is no need to support denormals; FP32, and therefore also BF16, offer more than enough range for deep learning training tasks.
  • FP32 accumulation after the multiply is essential to achieve sufficient numerical behavior on an application level.
  • Hardware exception handling is not needed as this is a performance optimization; industry is designing algorithms around checking inf/NaN.

For more complete information about compiler optimizations, see our Optimization Notice.