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@borg323 borg323 released this Jun 16, 2021

  • Multigather is now made the default (and also improved). Some search settings
    have changed meaning, so if you have modified values please discard them.
    Specifically, max-collision-events, max-collision-visits and
    max-out-of-order-evals-factor have changed default values, but other options
    also affect the search. Similarly, check that your gui is not caching the old
  • Performance improvements for the cuda/cudnn backends.
  • Support for policy focus during training.
  • Larger/stronger 15b default net for all packages except android, blas and dnnl
    that get a new 10b network.
  • The distributed binaries come with the mimalloc memory allocator for better
    performance when a large tree has to be destroyed (e.g. after an unexpected
  • The legacy time manager will use more time for the first move after a long
    book line.
  • The --preload command line flag will initialize the backend and load the
    network during startup.
  • A 'fen' command was added as a UCI extension to print the current position.
  • Experimental onednn backend for recent intel cpus and gpus.
3 people reacted
Assets 12

@Tilps Tilps released this Feb 17, 2021

  • Fix additional cases where 'invalid move' could be incorrectly reported.
  • Replace WDL softmax in cudnn backend with same implementation as cuda
    backend. This fixes some inaccuracy issues that were causing training
    data to be rejected at a fairly low frequency.
  • Ensure that training data Q/D pairs form valid WDL targets even if there
    is accumulated drift in calculation.
  • Fix for the calculation of the 'best q is proven' bit in training data.
  • Multiple fixes for timelosses and infinite instamoving in smooth time
    manager. Smooth time manager now made default after these fixes.
Assets 11

@Tilps Tilps released this Feb 6, 2021

  • Fix a bug which meant position ... moves ... didn't work if the moves went off the end of the existing tree. (Which happens normally when playing from an opening book.)
Assets 11

@Tilps Tilps released this Feb 6, 2021

Note: This version is very broken, do not attempt use it.

  • Multigather search inspired by Ceres. (Default is off. Note that the meaning of max-collision-events changes considerably when enabled and max-collision-visits will need to be set to a value close to previous values of max-collision-events in order to have similar search behavior.)
  • V6 training format with additional info for training experiments.
  • Updated default search parameters.
  • A better algorithm for the backendbench assistant.
  • Terminate search early if only 1 move isn't a proven loss.
  • Various build system changes.
Assets 11

@borg323 borg323 released this Oct 10, 2020

Starting with this release, we are distributing two packages for windows with Nvidia GPUs: the cuda package and the cudnn package. The cudnn package is what we used to distribute so far (but we called it cuda), and comes with the same versions of cuda and cudnn dlls we were using for the last few months. The new cuda package comes with cuda 11.1 dlls and requires at least version 456.38 of the windows Nvidia drivers, and should give better performance on RTX cards and in particular the new RTX 30XX cards.


  1. The cudnn package will work as-is in existing setups, but for the cuda package you may have to replace cudnn with cuda (or cuda-auto or cuda-fp16) as a backend (if specified) - this will certainly be necessary for multi-gpu setups.
  2. Some testing indicates that cuda 11.1 may be slower for GTX 10XX cards, so owners of older cards may want to stay with the cudnn package. If your testing shows otherwise do let us know.
Assets 10

@borg323 borg323 released this Oct 3, 2020

  • Fix for uninitialized variable that led to crashes with the cudnn backend.
  • Correct windows support for systems with more than 64 threads.
  • A new package is built for the cuda backend with cuda 11.1. The old cuda package is renamed to cudnn.

Note: The cuda package requires nvidia driver 456.38 or newer.

Assets 11

@borg323 borg323 released this Sep 28, 2020

  • Residual block fusion optimization for cudnn backend, that depends on custom_winograd=true. Enabled by default only for networks with up to 384 filters in fp16 mode and never in fp32 mode. Default can be overridden with --backend-opts=res_block_fusing=false to disable (or =true to enable).
  • New experimental cuda backend without cudnn dependency (cuda-auto, cuda and cuda-fp16 are available).
Assets 9

@borg323 borg323 released this Aug 28, 2020

  • Repetitions in the search tree are marked as draws, to explore more promising lines. Enabled by default (except in selfplay mode) use --two-fold-draws=false to disable.
  • Syzygy tablebase files can now be used in selfplay. Still need to add adjudication support before we can consider using this for training.
  • Default net updated to 703810.
  • Fix for book with CR/LF line endings.
  • Updated Eigen wrap to use new download link.

If you build from source, note that old versions of meson cannot download from the new Eigen download link. You will either have to update meson or build with -Dblas=false.

Assets 9