init: do not reject a config that sets only minCTAs or only maxCTAs - #2256
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EylonKrause wants to merge 1 commit into
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init: do not reject a config that sets only minCTAs or only maxCTAs#2256EylonKrause wants to merge 1 commit into
EylonKrause wants to merge 1 commit into
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The min/maxCTAs validation in parseCommConfig guards the <=0 checks with NCCL_CONFIG_UNDEF_INT but the minCTAs>maxCTAs check does not. Since unset fields are NCCL_CONFIG_UNDEF_INT (INT_MIN), setting only minCTAs (maxCTAs left unset) makes minCTAs>maxCTAs (>INT_MIN) true, so a valid config is rejected with ncclInvalidArgument. Guard the comparison with the same UNDEF checks used by the sibling clauses. Signed-off-by: EylonKrause <eylon1909@gmail.com>
Member
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Seems like an obvious fix indeed. @xiaofanl-nvidia let's merge this asap. |
Collaborator
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/mirror dev |
Collaborator
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Thanks, @EylonKrause , this was a good find! I've merged it to dev. Thank you for your contribution! |
Author
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Thanks @marksantesson! Glad it made it into dev — I'll keep an eye out for it in the next release. |
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Description
parseCommConfigvalidates theminCTAs/maxCTAsconfig fields with three clauses. The first two guard the unset sentinelNCCL_CONFIG_UNDEF_INTbefore their<= 0checks, but the third clause —internalConfigPtr->minCTAs > internalConfigPtr->maxCTAs— does not. Unset config fields areNCCL_CONFIG_UNDEF_INT(INT_MIN), so a config that sets onlyminCTAs(leavingmaxCTAsunset) makesminCTAs > INT_MINtrue, andncclCommInitRankConfig/ncclCommSplitreject an otherwise-valid configuration withncclInvalidArgument.minCTAsandmaxCTAsare documented as independently settable, so setting just one should be allowed.Related Issues
None.
Changes & Impact
src/init.cc(parseCommConfig): guard theminCTAs > maxCTAscomparison with the sameNCCL_CONFIG_UNDEF_INTchecks the two sibling clauses already use, so it only fires when both bounds are actually set. A genuinely inverted pair (e.g.minCTAs=16, maxCTAs=4) is still rejected. Non-breaking.Performance Impact
None.
Testing
make src.build.ncclCommInitRankConfig(1 rank),config.minCTAs=4,maxCTAsleft unset:init.cc NCCL WARN Invalid config min/max channels attribute value 4/-2147483648→ returnsncclInvalidArgument(-2147483648is the unsetmaxCTAssentinel).ncclSuccess.