[Bugfix] compressed-tensors: allow int8 grouped WNA16 MoE on Marlin - #47154
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The num_bits==8 branch of CompressedTensorsWNA16MarlinMoEMethod asserted
group_size == -1, rejecting int8 experts quantized with a group size (e.g.
group_size=128) even though Marlin supports them: uint8b128 is a supported
quant type and MARLIN_SUPPORTED_GROUP_SIZES includes 128, and
check_moe_marlin_supports_layer already admits group_size in {-1,32,64,128}
(so the method is selected and then asserts against itself). Drop the assert;
the scale key (kInt8StaticGroupScale) is unchanged and mirrors the int4 branch,
which already uses one *StaticGroupScale key across non-32 group sizes.
Validated on a mixed-precision int4/int8 compressed-tensors MoE checkpoint
(int8 layers at group_size=128): loads on the Marlin backend and produces
output byte-identical to the non-Marlin WNA16 MoE path and to bf16.
Signed-off-by: Joe Rowell <joerowell4@gmail.com>
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LGTM, thanks for the work!
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The num_bits==8 branch of CompressedTensorsWNA16MarlinMoEMethod asserted group_size == -1, rejecting int8 experts quantized with a group size (e.g. group_size=128) even though Marlin supports them: uint8b128 is a supported quant type and MARLIN_SUPPORTED_GROUP_SIZES includes 128, and check_moe_marlin_supports_layer already admits group_size in {-1,32,64,128} (so the method is selected and then asserts against itself).
The assert isn't needed, and crucially, it unblocks mixed-precision INT models (such as
poolside/Laguna-XS.2-INT4, which has INT4 & INT8 layers).Purpose
Test Plan
Test Result
Essential Elements of an Effective PR Description Checklist
supported_models.mdandexamplesfor a new model.