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@brb-nv brb-nv commented Aug 19, 2025

Description

We don't support context parallelism in disaggregated serving today. This MR makes initial no-op changes API introducing the concept of context parallelism in disaggregated serving. CP remains unsupported.

Test Coverage

Existing unit tests for disaggregated serving.

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Summary by CodeRabbit

  • New Features
    • Added context-level parallelism to cache handling, enabling 3D parallelism (tensor, pipeline, context); status/equality and string output now reflect the new dimension.
  • Tests
    • Expanded tests and parameters to validate context parallelism across context and generation flows, including DP scenarios and communicator setup.
  • Refactor
    • Public constructors updated to accept context-parallelism for consistent APIs.
  • Chores
    • Cache formatters now warn and reject unsupported multi-context setups.

@brb-nv brb-nv requested review from Tabrizian and chuangz0 August 19, 2025 23:40
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📝 Walkthrough

Walkthrough

Adds a context-parallelism (cp) dimension to CacheState and its ParallelConfig, threads cp through constructors, equality, serialization, stringification, and tests, and adds runtime guards in cache formatters to reject non-1 context-parallelism.

Changes

Cohort / File(s) Summary
Cache state API & equality
cpp/include/tensorrt_llm/executor/dataTransceiverState.h
Adds ParallelConfig::mContextParallelism; extends CacheState constructors to accept contextParallelism; updates ParallelConfig::operator==; adds AttentionConfig::operator==; includes attention and cp in CacheState::operator==; extends CacheState::toString() to include cp.
Serialization
cpp/tensorrt_llm/executor/serialization.cpp
Serialization/deserialization now read/write mParallelConfig.mContextParallelism; serializedSize updated; deserializeCacheState supplies cp to reconstructed CacheState.
Cache formatting runtime guards
cpp/tensorrt_llm/batch_manager/cacheFormatter.cpp, cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp
Add checks that require both self and destination mContextParallelism == 1; log a warning and return false when cp != 1, short-circuiting compatibility/unformat paths.
Batch manager tests (3D parallelism wiring)
cpp/tests/batch_manager/cacheTransceiverTest.cpp
All CacheState constructions updated to include cp; test parametrization (AsymmetricTestParam) extended with cp ints; setUpCommunicator signature expanded to accept contextCp/genCp; test scaffolding adds mCpSize/mContextCpSize and propagates cp through DP and rank calculations.
Unit test update
cpp/tests/unit_tests/executor/serializeUtilsTest.cpp, cpp/tests/unit_tests/executor/agentCommTest.cpp
Adjusts CacheState constructions to pass the additional contextParallelism integer before nvinfer1::DataType.

Sequence Diagram(s)

sequenceDiagram
    participant Caller as CacheFormatter::inquireSupport
    participant Self as selfConfig
    participant Dest as destConfig
    Note over Caller,Self: Validate configs
    Caller->>Self: read mContextParallelism (cp_self)
    Caller->>Dest: read mContextParallelism (cp_dest)
    alt cp_self != 1 or cp_dest != 1
        Caller->>Caller: log "context parallelism is not currently supported"
        Caller-->>Caller: return false
    else cp_self == 1 and cp_dest == 1
        Caller->>Caller: continue other compatibility checks (TP/PP/DP)
        Caller-->>Caller: return result
    end
Loading
sequenceDiagram
    participant Serializer as serializeCacheState
    participant Stream as OutputStream
    participant Deserializer as deserializeCacheState
    participant Input as InputStream
    Serializer->>Stream: write ParallelConfig fields (tp, pp)
    Serializer->>Stream: write ParallelConfig.mContextParallelism (cp)
    Serializer->>Stream: write other CacheState fields
    Deserializer->>Input: read ParallelConfig fields (tp, pp)
    Deserializer->>Input: read ParallelConfig.mContextParallelism (cp)
    Deserializer->>Deserializer: construct CacheState(..., pipelineParallelism, contextParallelism, DataType, ...)
Loading

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

Suggested labels

KV-Cache Management

Suggested reviewers

  • chuangz0
  • pcastonguay

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@brb-nv brb-nv changed the title [None][chore] Initial updates to support Context Parallelism in disaggregated serving [None][chore] Initial updates to support context parallelism in disaggregated serving Aug 19, 2025
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Actionable comments posted: 0

🧹 Nitpick comments (3)
cpp/include/tensorrt_llm/executor/dataTransceiverState.h (2)

160-179: toString includes cp; add missing header for stringstream

  • Including cp in string output keeps diagnostics aligned with the new dimension — good.
  • Minor nit: this file uses std::stringstream in multiple toString() implementations but doesn’t include <sstream>. Please add it to the includes to avoid relying on transitive headers.

Add near the other standard headers:

#include <sstream>

Also applies to: 172-172


51-59: Header guards vs pragma once

Project guidelines require header include guards named like TRTLLM_<FILENAME>_H. This header uses #pragma once. Consider switching to a guard to align with the codebase conventions.

cpp/tests/unit_tests/executor/serializeUtilsTest.cpp (1)

1336-1353: Broaden test parametrization to exercise cp>1 configurations

Most instantiations fix cp to 1. To cover the new dimension meaningfully, consider adding cases with contextCp and/or genCp > 1 (e.g., {1, 2}) where feasible so rank-domain partitioning and target mapping logic are exercised under non-trivial cp.

Also applies to: 1355-1358, 1361-1371, 1372-1377, 1379-1388, 1390-1411, 1413-1426

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📥 Commits

Reviewing files that changed from the base of the PR and between c02592d and d1d2331.

📒 Files selected for processing (4)
  • cpp/include/tensorrt_llm/executor/dataTransceiverState.h (5 hunks)
  • cpp/tensorrt_llm/executor/serialization.cpp (3 hunks)
  • cpp/tests/batch_manager/cacheTransceiverTest.cpp (21 hunks)
  • cpp/tests/unit_tests/executor/serializeUtilsTest.cpp (1 hunks)
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Files:

  • cpp/tests/unit_tests/executor/serializeUtilsTest.cpp
  • cpp/include/tensorrt_llm/executor/dataTransceiverState.h
  • cpp/tensorrt_llm/executor/serialization.cpp
  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
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Prefer anonymous namespaces over static for internal linkage of functions
Every defined function must be called at least once (no unused methods)

Files:

  • cpp/tests/unit_tests/executor/serializeUtilsTest.cpp
  • cpp/tensorrt_llm/executor/serialization.cpp
  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
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Files:

  • cpp/tests/unit_tests/executor/serializeUtilsTest.cpp
  • cpp/include/tensorrt_llm/executor/dataTransceiverState.h
  • cpp/tensorrt_llm/executor/serialization.cpp
  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
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Files:

  • cpp/tests/unit_tests/executor/serializeUtilsTest.cpp
  • cpp/include/tensorrt_llm/executor/dataTransceiverState.h
  • cpp/tensorrt_llm/executor/serialization.cpp
  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
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🧠 Learnings (2)
📚 Learning: 2025-08-14T21:04:50.208Z
Learnt from: thorjohnsen
PR: NVIDIA/TensorRT-LLM#6910
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:0-0
Timestamp: 2025-08-14T21:04:50.208Z
Learning: In KV cache onboarding logic during prefill in cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp, when calculating which blocks fall within the attention window, use getTokensPerBlock() to advance token indices rather than block->getUniqueTokens().size(), because the calculation needs to consider the post-prefill state where blocks will be filled to capacity, not their current token count.

Applied to files:

  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
📚 Learning: 2025-08-15T06:46:54.853Z
Learnt from: eopXD
PR: NVIDIA/TensorRT-LLM#6767
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:0-0
Timestamp: 2025-08-15T06:46:54.853Z
Learning: In cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp addToken function, newly allocated blocks are unshared by design. The beam search path in addToken (when sequence.getNumTokens() > windowSize) is currently broken/non-functional with SWA, so the block allocation doesn't follow a shared-then-unshared pattern.

Applied to files:

  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
🧬 Code Graph Analysis (3)
cpp/include/tensorrt_llm/executor/dataTransceiverState.h (2)
cpp/tests/unit_tests/kernels/decodingKernelTest.cpp (1)
  • tensorParallelism (346-372)
cpp/include/tensorrt_llm/batch_manager/cacheTransceiver.h (1)
  • nodiscard (67-90)
cpp/tensorrt_llm/executor/serialization.cpp (1)
cpp/tests/unit_tests/kernels/decodingKernelTest.cpp (1)
  • tensorParallelism (346-372)
cpp/tests/batch_manager/cacheTransceiverTest.cpp (2)
cpp/tests/unit_tests/kernels/decodingKernelTest.cpp (1)
  • tensorParallelism (346-372)
cpp/tests/unit_tests/batch_manager/cacheTransBufferTest.cpp (4)
  • numLayers (32-69)
  • numLayers (32-33)
  • numLayers (77-88)
  • numLayers (77-77)
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🔇 Additional comments (19)
cpp/include/tensorrt_llm/executor/dataTransceiverState.h (6)

55-56: CP threaded into ParallelConfig via WorldConfig — verify DP rank/size semantics

Good to see cp added here. One sanity check: mParallelConfig{ tp, pp, cp, enableAttentionDP, DPrank=worldConfig.getTensorParallelRank(), DPsize=worldConfig.getTensorParallelism() } assumes Attention DP uses the TP domain for rank/size. If the DP domain can diverge from TP in some configurations, we should thread a dedicated DP-size getter from WorldConfig instead of reusing TP.


62-71: Ctor overload updated to include contextParallelism — looks correct

The parameter ordering and the initialization of mParallelConfig with the new contextParallelism are consistent.


73-82: Second ctor overload with contextParallelism — looks correct

The braced initialization maintains argument order and matches the struct layout.


84-88: Equality now includes AttentionConfig — good catch

Including mAttentionConfig in CacheState::operator== avoids false positives when attention settings differ.


103-118: ParallelConfig extended with mContextParallelism and equality updated — OK

Field addition and operator== update are consistent and non-ambiguous.


130-134: Add AttentionConfig::operator== — OK

This enables clean structural equality across cache states.

cpp/tests/unit_tests/executor/serializeUtilsTest.cpp (6)

726-733: ContextPhaseParams test updated to pass cp via CacheState — OK

The constructor call now includes the cp argument before DataType. This aligns with the new API.


136-153: WorldConfig/CacheState equality test extended with cp — OK

  • Introducing contextParallelism and threading it to WorldConfig validates the 3D parallel config path.
  • The state0 == state1 check remains coherent with the updated equality semantics.

510-511: Param tuple and setup signature expanded for cp — double-check tuple-index mapping

The AsymmetricTestParam now has cp for both context and generation. The setUpCommunicator signature matches. Please verify all downstream uses of std::get<...>(param) reflect the new indices throughout the test body and instantiation blocks.

Also applies to: 520-522


704-709: CacheState construction propagates cp in both context and generation paths — OK

  • mCacheState and mContextCacheState include cp in their parallel config.
  • The DP-size remains tied to TP-size (DPsize = mContextTpSize), consistent with the existing DP domain assumptions.

Also applies to: 867-871


1138-1156: Parameter extraction includes cp for context and generation — OK

The expanded tuple deconstruction is consistent with the updated AsymmetricTestParam.


1444-1447: Target tests updated to include cp — OK

The helper verifyContext and subsequent scenarios include cp in the constructed CacheState. Looks consistent with the new API and expected behavior.

Also applies to: 1519-1523, 1555-1563

cpp/tensorrt_llm/executor/serialization.cpp (2)

534-535: Wire format change: inserted mContextParallelism — confirm compatibility expectations

CacheState serialization/deserialization now writes/reads mContextParallelism between mPipelineParallelism and mEnableAttentionDP. This alters the wire format.

  • If you guarantee single-version comms (both ends upgraded together) and no persisted artifacts depend on the previous layout, this is fine.
  • If cross-version communication or long-lived persisted buffers are possible, consider versioning the CacheState encoding (or guarding cp with a feature/version tag) to keep backward compatibility. Without a version, older readers will misinterpret fields.

I can help sketch a minimal version-tag pattern if needed.

Also applies to: 552-553, 569-570


541-543: Constructor call updated to pass contextParallelism — OK

The deserializer now reconstructs CacheState with the new cp parameter in the correct position.

cpp/tests/batch_manager/cacheTransceiverTest.cpp (5)

102-103: RequestInfoTest: CacheState now includes cp — OK

The basic roundtrip includes cp in CacheState, matching the new ctor.


136-153: CacheConfigTest: cp included in worldConfig and equality path — OK

Using contextParallelism in WorldConfig and verifying CacheState equality across constructors looks sound.


169-169: Mocks updated to construct CacheState with cp — OK

The mocked DataTransceiverState includes cp in CacheState consistently across sender/requester tests.

Also applies to: 221-222


704-709: AsymmetricalCacheTest: propagate cp in both gen and context CacheState — OK

  • mCacheState and mContextCacheState both include mCpSize/mContextCpSize.
  • DP rank/size parameters remain bound to TP, consistent with the rest of the suite.

1138-1147: Param deconstruction: add cp indices (contextCp, genCp) — OK

Mapping of tuple indices to variables is coherent with the updated AsymmetricTestParam definition.

@brb-nv brb-nv requested a review from a team as a code owner August 20, 2025 00:25
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Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)
cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (1)

555-560: Bug: duplicated self check likely intended to validate dest as well.

Both sides of the condition reference selfConfig, so destConfig is never validated here. This can incorrectly accept unsupported configurations where dest heads-per-layer != 1.

-    if ((selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1)
-        || (selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1))
+    if ((selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1)
+        || (destConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1))
     {
-        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: only support MLA");
+        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: only support mNbKvHeadsPerLayer == 1 for MLA");
         return false;
     }
🧹 Nitpick comments (4)
cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (2)

573-577: Context-parallelism guard added — good; consider logging actual values.

Guarding CP>1 here is aligned with the PR goals of a no-op API introduction. To make triage easier when this trips, include the self/dest CP values in the warning.

-    if (selfConfig.getParallelConfig().mContextParallelism != 1 || destConfig.getParallelConfig().mContextParallelism != 1)
+    if (selfConfig.getParallelConfig().mContextParallelism != 1 || destConfig.getParallelConfig().mContextParallelism != 1)
     {
-        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: context parallelism is not currently supported");
+        TLLM_LOG_WARNING(
+            "MLACacheFormatter::inquireSupport: context parallelism is not currently supported (self=%d, dest=%d)",
+            selfConfig.getParallelConfig().mContextParallelism,
+            destConfig.getParallelConfig().mContextParallelism);
         return false;
     }

562-566: Redundant kvFactor check; remove duplication.

mKvFactor equality is already validated earlier (Lines 522-526). Keeping both adds noise and maintenance overhead with no benefit.

-    if (selfConfig.getAttentionConfig().mKvFactor != destConfig.getAttentionConfig().mKvFactor)
-    {
-        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: only support same kv factor");
-        return false;
-    }
cpp/tensorrt_llm/batch_manager/cacheFormatter.cpp (2)

825-829: Context-parallelism guard added — good; include CP values for better diagnostics.

The no-op gating for CP>1 is correct. Emitting the actual CP values simplifies debugging and log triage.

-    if (selfConfig.getParallelConfig().mContextParallelism != 1 || destConfig.getParallelConfig().mContextParallelism != 1)
+    if (selfConfig.getParallelConfig().mContextParallelism != 1 || destConfig.getParallelConfig().mContextParallelism != 1)
     {
-        TLLM_LOG_WARNING("CacheFormatter::inquireSupport: context parallelism is not currently supported");
+        TLLM_LOG_WARNING(
+            "CacheFormatter::inquireSupport: context parallelism is not currently supported (self=%d, dest=%d)",
+            selfConfig.getParallelConfig().mContextParallelism,
+            destConfig.getParallelConfig().mContextParallelism);
         return false;
     }

825-829: DRY: consider extracting a shared helper for the CP gate used in both formatters.

Both CacheFormatter and MLACacheFormatter now perform the same CP==1 check and warning. A small inline utility (e.g., in a common header) would reduce duplication and keep messages consistent.

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📚 Learning: 2025-08-06T08:18:28.669Z
Learnt from: zhengd-nv
PR: NVIDIA/TensorRT-LLM#6633
File: cpp/tensorrt_llm/batch_manager/dataTransceiverImpl.cpp:145-155
Timestamp: 2025-08-06T08:18:28.669Z
Learning: In cpp/tensorrt_llm/batch_manager/dataTransceiverImpl.cpp, the existing `mMtxForMap` mutex in DataSenderImpl is sufficient to synchronize measurement file operations in the `release` method, as all file operations occur within the same critical section that protects the `mRequestToSession` map access.

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📚 Learning: 2025-08-15T06:46:54.853Z
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PR: NVIDIA/TensorRT-LLM#6767
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:0-0
Timestamp: 2025-08-15T06:46:54.853Z
Learning: In cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp addToken function, newly allocated blocks are unshared by design. The beam search path in addToken (when sequence.getNumTokens() > windowSize) is currently broken/non-functional with SWA, so the block allocation doesn't follow a shared-then-unshared pattern.

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cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (1)

573-577: Summary mismatch: change is in inquireSupport, not unformat.

The AI summary mentions adding the CP guard in unformat(); the actual guard here is in inquireSupport().

@brb-nv brb-nv force-pushed the user/brb/helix-in-disagg-initial branch 2 times, most recently from 42694f6 to 0297181 Compare August 20, 2025 00:30
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⚠️ Outside diff range comments (2)
cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (1)

555-557: Bug: second operand checks self twice; dest never validated.

The intent is to enforce single KV head for both self and dest, but the second condition repeats self instead of checking dest.

Apply this fix:

-    if ((selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1)
-        || (selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1))
+    if ((selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1)
+        || (destConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1))
     {
         TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: only support MLA");
         return false;
     }
cpp/tests/batch_manager/cacheTransceiverTest.cpp (1)

659-662: Fix cacheType shadowing to enable K-only mode

In cpp/tests/batch_manager/cacheTransceiverTest.cpp (around lines 659–662), the inner auto cacheType shadows the outer variable, so kSELFKONLY is never applied. Replace the inner declaration with an assignment:

@@ -659,7 +659,7 @@
         CacheType cacheType = CacheType::kSELF;
         if (kvFactor == 1)
         {
-            auto cacheType = CacheType::kSELFKONLY;
+            cacheType = CacheType::kSELFKONLY;
         }

After applying this change, please re-run the tests covering kvFactor == 1 (MLA paths) to confirm that K-only behavior is now exercised.

🧹 Nitpick comments (6)
cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (4)

562-566: Duplicate kvFactor check; remove redundancy.

This duplicates the earlier kvFactor equality check (Lines 522–526). Keep one to avoid confusion and drift.

-    if (selfConfig.getAttentionConfig().mKvFactor != destConfig.getAttentionConfig().mKvFactor)
-    {
-        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: only support same kv factor");
-        return false;
-    }

33-36: Missing include for unordered_set.

This file uses std::unordered_set (Lines 528, 536) but does not include <unordered_set>. Relying on transitive includes is brittle.

 #include <cstddef>
 #include <cstdint>
 #include <future>
+#include <unordered_set>

602-611: Log prefix consistency nit: use MLACacheFormatter in warnings.

These messages mention “CacheFormatter::inquireSupport” inside MLACacheFormatter. Aligning the prefix eases debugging and grep-ability.

-        TLLM_LOG_WARNING("CacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d",
+        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d",
             selfNumLayers, selfPPSize);
...
-        TLLM_LOG_WARNING("CacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d ",
+        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d ",
             destNumLayers, destPPSize);

567-572: Optional: guard division by zero when DP is enabled.

If mEnableAttentionDP is true while mDPsize is accidentally zero, modulo will UB. A pre-check makes this resilient.

-    if (selfConfig.getParallelConfig().mEnableAttentionDP
-        && (selfConfig.getParallelConfig().mTensorParallelism % selfConfig.getParallelConfig().mDPsize != 0))
+    if (selfConfig.getParallelConfig().mEnableAttentionDP)
     {
-        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: TP size must be divisible by DP size");
-        return false;
+        if (selfConfig.getParallelConfig().mDPsize == 0)
+        {
+            TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: DP size must be > 0 when attention DP is enabled");
+            return false;
+        }
+        if (selfConfig.getParallelConfig().mTensorParallelism % selfConfig.getParallelConfig().mDPsize != 0)
+        {
+            TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: TP size must be divisible by DP size");
+            return false;
+        }
     }

Make the analogous change for destConfig as well.

Also applies to: 579-583

cpp/include/tensorrt_llm/executor/dataTransceiverState.h (2)

62-71: Constructor overloads with contextParallelism are consistent.

Signatures are orderly (tp, pp, cp, dtype, attentionType, kvFactor, DP...). This keeps call sites explicit and avoids ambiguity.

Consider a convenience overload that defaults contextParallelism=1 to reduce churn in simple call sites.

Also applies to: 73-82


17-17: Prefer include guards over pragma once per project guideline.

Headers must use include guards named TRTLLM__H. Replace or augment #pragma once.

You can wrap the header like this (file-wide change):

#ifndef TRTLLM_DATA_TRANSCEIVER_STATE_H
#define TRTLLM_DATA_TRANSCEIVER_STATE_H
// existing contents, keep #pragma once if you prefer, but guards are required by guideline
#pragma once

// ... file content ...

#endif // TRTLLM_DATA_TRANSCEIVER_STATE_H
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🧠 Learnings (2)
📚 Learning: 2025-08-14T21:04:50.208Z
Learnt from: thorjohnsen
PR: NVIDIA/TensorRT-LLM#6910
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:0-0
Timestamp: 2025-08-14T21:04:50.208Z
Learning: In KV cache onboarding logic during prefill in cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp, when calculating which blocks fall within the attention window, use getTokensPerBlock() to advance token indices rather than block->getUniqueTokens().size(), because the calculation needs to consider the post-prefill state where blocks will be filled to capacity, not their current token count.

Applied to files:

  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
📚 Learning: 2025-08-15T06:46:54.853Z
Learnt from: eopXD
PR: NVIDIA/TensorRT-LLM#6767
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:0-0
Timestamp: 2025-08-15T06:46:54.853Z
Learning: In cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp addToken function, newly allocated blocks are unshared by design. The beam search path in addToken (when sequence.getNumTokens() > windowSize) is currently broken/non-functional with SWA, so the block allocation doesn't follow a shared-then-unshared pattern.

Applied to files:

  • cpp/tests/batch_manager/cacheTransceiverTest.cpp
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🔇 Additional comments (17)
cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (1)

573-577: Guarding on context parallelism (cp) is correct for now; message is clear.

Rejecting cp != 1 keeps runtime behavior unchanged while introducing the cp concept. This matches the PR’s “no-op” goal.

Do all callers route through inquireSupport() before invoking format/unformat? If not, we should add equivalent defensive guards (or an early no-op) in those paths too to prevent accidental misuse. I can help audit the call graph if needed.

cpp/include/tensorrt_llm/executor/dataTransceiverState.h (5)

55-57: Threading cp and DP defaults via WorldConfig looks good.

mContextParallelism is sourced from worldConfig; DP rank/size default to TP rank/size which matches how tests initialize DP. No behavior change until cp != 1 is used.

Confirm Serialization handles mContextParallelism consistently (write, read, and serializedSize). The PR description says it’s done; if you want, I can cross-check.


84-88: Include AttentionConfig in equality — good catch.

Adding attention configuration to CacheState equality prevents subtle mismatches from going unnoticed.


103-118: ParallelConfig gains cp and reflects it in equality — aligned with the new dimension.


130-134: AttentionConfig operator== is appropriate.

Explicit equality helps the higher-level CacheState::operator== stay clean.


172-172: toString includes cp — good for observability.

cpp/tests/batch_manager/cacheTransceiverTest.cpp (11)

102-102: CacheState ctor updated with cp — serialization/equality Basic test remains valid.

Passing cp=8 here is fine since this test only round-trips RequestInfo; it won’t hit runtime guards.


136-152: WorldConfig and CacheState equality test now include cp — good coverage.

Adding contextParallelism to WorldConfig and asserting equality of two CacheStates across ctor paths ensures the new field is wired correctly.


168-172: Mock paths pass cp=1 — aligned with runtime guard.

Keeps tests green while cp is a no-op.

Also applies to: 221-223


322-323: Symmetric test CacheState uses cp=1 — OK.


510-522: Param pack extended for cp; setup signature updated accordingly.

The tuple order and setup parameters are consistent (contextTp, contextPp, contextCp, genTp, genPp, genCp, ...).

Ensure all INSTANTIATE_TEST_CASE_P tuples align with the new order; from the diff they do. If failures pop up, it’ll most likely be due to misordered params.


572-592: cp routed into per-instance state — good.

mCpSize/mContextCpSize recorded; ranks and sizes computed unchanged otherwise.


704-709: cp propagated into CacheState for both generation and context paths.

This matches how the cache formatter’s support checks will read cp=1 and proceed.


867-872: DP test helper reconstructs CacheState including cp — correct.


1103-1105: Members extended with cp sizes — consistent with setup paths.


1336-1371: Test matrices set cp=1 — compatible with current runtime restriction.

All INSTANTIATE_* macros fix cp to 1 for both context and generation, which avoids tripping the new guard.

Also applies to: 1372-1427


1456-1460: Target rank computation tests incorporate cp — no-op as cp=1.

These constructions keep the existing expectations intact while threading cp forward.

Also applies to: 1536-1541, 1643-1648

@brb-nv brb-nv force-pushed the user/brb/helix-in-disagg-initial branch from 0297181 to 07ae648 Compare August 20, 2025 00:39
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brb-nv commented Aug 20, 2025

/bot run

@brb-nv brb-nv changed the title [None][chore] Initial updates to support context parallelism in disaggregated serving [None][chore] No-op changes to support context parallelism in disaggregated serving later Aug 20, 2025
@brb-nv brb-nv requested a review from MatthiasKohl August 20, 2025 00:46
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PR_Github #15832 [ run ] completed with state SUCCESS
/LLM/main/L0_MergeRequest_PR pipeline #11900 completed with status: 'FAILURE'

@brb-nv brb-nv force-pushed the user/brb/helix-in-disagg-initial branch from 07ae648 to cc239f9 Compare August 20, 2025 18:54
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/bot run

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Actionable comments posted: 1

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (2)
cpp/include/tensorrt_llm/executor/dataTransceiverState.h (1)

24-28: Missing include (used by toString methods)

This header uses std::stringstream in multiple toString() implementations but doesn’t include . Relying on transitive includes is brittle and can cause downstream compile failures.

Apply:

 #include <cstdint>
 #include <string>
+#include <sstream>
 #include <variant>
 #include <vector>

Also applies to: 160-180, 197-207, 219-223, 243-246, 324-354, 400-412

cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (1)

555-574: Bug: duplicate self check; dest heads-per-layer is never validated

This condition checks self twice and never validates dest, so it always rejects unless self has exactly one head. Likely intended to check both self and dest.

Apply:

-    if ((selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1)
-        || (selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1))
+    if (selfConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1
+        || destConfig.getModelConfig().mNbKvHeadsPerLayer.at(0) != 1)
     {
         TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: only support MLA");
         return false;
     }
♻️ Duplicate comments (1)
cpp/include/tensorrt_llm/executor/dataTransceiverState.h (1)

84-88: Equality now includes AttentionConfig — good call

Including AttentionConfig in CacheState::operator== and adding AttentionConfig::operator== closes a real gap (past reviewers questioned omitting attention config from equality). This aligns hashing/equality with the full semantics of the cache layout.

Also applies to: 130-134

🧹 Nitpick comments (4)
cpp/include/tensorrt_llm/executor/dataTransceiverState.h (1)

62-71: Constructor API: consider a compatibility overload (cp defaults to 1)

Threading cp through the ctors is fine. To ease downstream churn (and align with “no-op” runtime behavior), consider keeping a backwards-compatible overload that defaults contextParallelism=1 and forwards to the new ctor. This avoids breaking external consumers that haven’t been migrated yet.

Apply for both vector-based and scalar nbKvHeads overloads:

+    // Back-compat overload: defaults contextParallelism to 1
+    CacheState(std::vector<SizeType32> nbKvHeadPerLayer, SizeType32 sizePerHead, SizeType32 tokensPerBlock,
+        SizeType32 tensorParallelism, SizeType32 pipelineParallelism, nvinfer1::DataType dataType,
+        AttentionType attentionType = AttentionType::kDEFAULT, int kvFactor = 2,
+        bool enableAttentionDP = false, int DPrank = 0, int DPsize = 0)
+        : CacheState(std::move(nbKvHeadPerLayer), sizePerHead, tokensPerBlock, tensorParallelism, pipelineParallelism,
+            /*contextParallelism=*/1, dataType, attentionType, kvFactor, enableAttentionDP, DPrank, DPsize)
+    {}
+
+    // Back-compat overload: defaults contextParallelism to 1
+    CacheState(SizeType32 nbAttentionLayers, SizeType32 nbKvHeads, SizeType32 sizePerHead, SizeType32 tokensPerBlock,
+        SizeType32 tensorParallelism, SizeType32 pipelineParallelism, nvinfer1::DataType dataType,
+        AttentionType attentionType = AttentionType::kDEFAULT, int kvFactor = 2,
+        bool enableAttentionDP = false, int DPrank = 0, int DPsize = 0)
+        : CacheState(nbAttentionLayers, nbKvHeads, sizePerHead, tokensPerBlock, tensorParallelism, pipelineParallelism,
+            /*contextParallelism=*/1, dataType, attentionType, kvFactor, enableAttentionDP, DPrank, DPsize)
+    {}

Also applies to: 73-82

cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (3)

599-607: Nit: inconsistent logger prefix (“CacheFormatter” vs “MLACacheFormatter”)

For clarity and grep-ability, keep the same component prefix.

-        TLLM_LOG_WARNING("CacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d",
+        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d",
             selfNumLayers, selfPPSize);
...
-        TLLM_LOG_WARNING("CacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d ",
+        TLLM_LOG_WARNING("MLACacheFormatter::inquireSupport: layers %d must be divisible by pipeline parallelism :%d ",
             destNumLayers, destPPSize);

536-538: Type consistency: use SizeType32 for dest set as well

setVecDest currently uses int, while setVecSelf uses SizeType32. Align types to avoid narrowing and maintain consistency.

-    std::unordered_set<int> setVecDest{
+    std::unordered_set<SizeType32> setVecDest{
         destConfig.getModelConfig().mNbKvHeadsPerLayer.begin(), destConfig.getModelConfig().mNbKvHeadsPerLayer.end()};

165-171: Spelling: agentConnnecion → agentConnection

Minor naming fix improves readability.

-    auto* agentConnnecion = dynamic_cast<executor::kv_cache::AgentConnection const*>(connections[0]);
-    if (agentConnnecion != nullptr)
+    auto* agentConnection = dynamic_cast<executor::kv_cache::AgentConnection const*>(connections[0]);
+    if (agentConnection != nullptr)
     {
         TLLM_CHECK_WITH_INFO(bufferCoverTargetNum == pPDomainSize, "Agent need all buffer pre-allocated");
         TLLM_CHECK(onlyUseDynamicBuffer == false);
     }
-        auto* agentConnnecion = dynamic_cast<executor::kv_cache::AgentConnection const*>(connections[0]);
-        if (agentConnnecion != nullptr)
+        auto* agentConnection = dynamic_cast<executor::kv_cache::AgentConnection const*>(connections[0]);
+        if (agentConnection != nullptr)
         {
-            cacheBufferId = agentConnnecion->getCacheBufferId();
+            cacheBufferId = agentConnection->getCacheBufferId();
             TLLM_CHECK(cacheBufferId.has_value());
         }

Also applies to: 349-375

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📒 Files selected for processing (7)
  • cpp/include/tensorrt_llm/executor/dataTransceiverState.h (5 hunks)
  • cpp/tensorrt_llm/batch_manager/cacheFormatter.cpp (1 hunks)
  • cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (1 hunks)
  • cpp/tensorrt_llm/executor/serialization.cpp (3 hunks)
  • cpp/tests/batch_manager/cacheTransceiverTest.cpp (21 hunks)
  • cpp/tests/unit_tests/executor/agentCommTest.cpp (1 hunks)
  • cpp/tests/unit_tests/executor/serializeUtilsTest.cpp (1 hunks)
🚧 Files skipped from review as they are similar to previous changes (4)
  • cpp/tensorrt_llm/batch_manager/cacheFormatter.cpp
  • cpp/tests/unit_tests/executor/serializeUtilsTest.cpp
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🧠 Learnings (3)
📚 Learning: 2025-08-15T06:46:54.897Z
Learnt from: eopXD
PR: NVIDIA/TensorRT-LLM#6767
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:0-0
Timestamp: 2025-08-15T06:46:54.897Z
Learning: In cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp addToken function, newly allocated blocks are unshared by design. The beam search path in addToken (when sequence.getNumTokens() > windowSize) is currently broken/non-functional with SWA, so the block allocation doesn't follow a shared-then-unshared pattern.

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  • cpp/tests/unit_tests/executor/agentCommTest.cpp
📚 Learning: 2025-08-20T06:56:02.889Z
Learnt from: eopXD
PR: NVIDIA/TensorRT-LLM#6768
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:577-579
Timestamp: 2025-08-20T06:56:02.889Z
Learning: In cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp, maxSequenceLength is now enforced as a non-optional argument in the BlockManager constructor, so concerns about std::nullopt defaulting to 0 are not applicable. When windowSize > maxSequenceLength, a warning should be added instead of handling optional parameter cases.

Applied to files:

  • cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp
📚 Learning: 2025-08-14T21:04:50.248Z
Learnt from: thorjohnsen
PR: NVIDIA/TensorRT-LLM#6910
File: cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp:0-0
Timestamp: 2025-08-14T21:04:50.248Z
Learning: In KV cache onboarding logic during prefill in cpp/tensorrt_llm/batch_manager/kvCacheManager.cpp, when calculating which blocks fall within the attention window, use getTokensPerBlock() to advance token indices rather than block->getUniqueTokens().size(), because the calculation needs to consider the post-prefill state where blocks will be filled to capacity, not their current token count.

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🔇 Additional comments (3)
cpp/include/tensorrt_llm/executor/dataTransceiverState.h (1)

107-117: cp threaded through ParallelConfig and toString — LGTM

  • Adding mContextParallelism to ParallelConfig and its operator== is consistent.
  • Including cp in toString improves diagnostics.

Also applies to: 172-173

cpp/tests/unit_tests/executor/agentCommTest.cpp (1)

93-94: Test updated to pass cp — LGTM

The CacheState construction reflects the new cp argument (set to 1). Matches the “cp is wired but must be 1” runtime guards.

cpp/tensorrt_llm/batch_manager/mlaCacheFormatter.cpp (1)

567-574: Guarding cp!=1 in inquireSupport is correct for the current scope

Returning early with a clear warning keeps runtime behavior unchanged while cp is not supported. Message is explicit and actionable.

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PR_Github #15946 [ run ] triggered by Bot

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PR_Github #15946 [ run ] completed with state SUCCESS
/LLM/main/L0_MergeRequest_PR pipeline #11985 completed with status: 'SUCCESS'
Pipeline passed with automatic retried tests. Check the rerun report for details.

@brb-nv brb-nv enabled auto-merge (squash) August 21, 2025 15:21
@brb-nv brb-nv merged commit 9a2b44d into NVIDIA:main Aug 21, 2025
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