[nvbug/5374773] chore: Add a runtime flag to enable fail fast when attn window is too large to fit at least one sequence in KV cache

cpp/include/tensorrt_llm/executor/executor.h

@@ -1484,7 +1484,8 @@ class ExecutorConfig
         std::optional<GuidedDecodingConfig> guidedDecodingConfig = std::nullopt,
         std::optional<std::vector<AdditionalModelOutput>> additionalModelOutputs = std::nullopt,
         std::optional<CacheTransceiverConfig> cacheTransceiverConfig = std::nullopt,
-        bool gatherGenerationLogits = false, bool promptTableOffloading = false, bool enableTrtOverlap = false);
+        bool gatherGenerationLogits = false, bool promptTableOffloading = false, bool enableTrtOverlap = false,
+        bool failFastOnAttentionWindowTooLarge = false);
 
     [[nodiscard]] SizeType32 getMaxBeamWidth() const;
     [[nodiscard]] SchedulerConfig getSchedulerConfig() const;
@@ -1519,6 +1520,7 @@ class ExecutorConfig
     [[nodiscard]] bool getPromptTableOffloading() const;
     [[nodiscard]] std::optional<CacheTransceiverConfig> getCacheTransceiverConfig() const;
     [[nodiscard]] bool getEnableTrtOverlap() const;
+    [[nodiscard]] bool getFailFastOnAttentionWindowTooLarge() const;
 
     void setMaxBeamWidth(SizeType32 maxBeamWidth);
     void setMaxBatchSize(SizeType32 maxBatchSize);
@@ -1548,6 +1550,7 @@ class ExecutorConfig
     void setPromptTableOffloading(bool promptTableOffloading);
     void setCacheTransceiverConfig(CacheTransceiverConfig const& cacheTransceiverConfig);
     void setEnableTrtOverlap(bool enableTrtOverlap);
+    void setFailFastOnAttentionWindowTooLarge(bool failFastOnAttentionWindowTooLarge);
 
 private:
     friend class Serialization;
@@ -1634,6 +1637,10 @@ class ExecutorConfig
 
     /// @brief Controls whether preparation and TRT engine execution should be overlapped.
     bool mEnableTrtOverlap{false};
+
+    /// @brief Controls whether to fail fast when attention window is too large to fit even a single sequence in the KV
+    /// cache.
+    bool mFailFastOnAttentionWindowTooLarge{false};
 };
 
 struct KVCacheCreatedData

cpp/tensorrt_llm/batch_manager/trtGptModelInflightBatching.cpp

@@ -296,27 +296,27 @@ TrtGptModelInflightBatching::TrtGptModelInflightBatching(std::shared_ptr<nvinfer
 
         auto const [freePrimaryMemBytes, freeSecondaryMemBytes]
             = BaseKVCacheManager::calculateFreeMemBytes(mRuntime->getBufferManager(), kvCacheConfig);
-
         if (mModelConfig.useCrossAttention())
         {
             TLLM_CHECK_WITH_INFO(kvCacheConfig.getCrossKvCacheFraction().has_value(),
                 "Must set crossKvCacheFraction for encoder-decoder model");
             auto const crossKvCacheFraction = kvCacheConfig.getCrossKvCacheFraction().value();
             mKvCacheManager = createKvCacheManager(kvCacheConfig, KvCacheType::kSELF,
                 freePrimaryMemBytes * (1.0f - crossKvCacheFraction),
-                freeSecondaryMemBytes * (1.0f - crossKvCacheFraction), cacheTransPreAllocaSize);
-            mCrossKvCacheManager
-                = createKvCacheManager(kvCacheConfig, KvCacheType::kCROSS, freePrimaryMemBytes * crossKvCacheFraction,
-                    freeSecondaryMemBytes * crossKvCacheFraction, cacheTransPreAllocaSize);
+                freeSecondaryMemBytes * (1.0f - crossKvCacheFraction), cacheTransPreAllocaSize,
+                executorConfig.getFailFastOnAttentionWindowTooLarge());
+            mCrossKvCacheManager = createKvCacheManager(kvCacheConfig, KvCacheType::kCROSS,
+                freePrimaryMemBytes * crossKvCacheFraction, freeSecondaryMemBytes * crossKvCacheFraction,
+                cacheTransPreAllocaSize, executorConfig.getFailFastOnAttentionWindowTooLarge());
             TLLM_LOG_INFO("This is an Encoder-Decoder model, set %0.1f cross KV cache fraction based on the config.",
                 crossKvCacheFraction);
         }
         else
         {
             TLLM_CHECK_WITH_INFO(!kvCacheConfig.getCrossKvCacheFraction().has_value(),
                 "Do not set crossKvCacheFraction for decoder-only model");
-            mKvCacheManager = createKvCacheManager(
-                kvCacheConfig, KvCacheType::kSELF, freePrimaryMemBytes, freeSecondaryMemBytes, cacheTransPreAllocaSize);
+            mKvCacheManager = createKvCacheManager(kvCacheConfig, KvCacheType::kSELF, freePrimaryMemBytes,
+                freeSecondaryMemBytes, cacheTransPreAllocaSize, executorConfig.getFailFastOnAttentionWindowTooLarge());
         }
 
         mCacheTransceiver
@@ -550,7 +550,8 @@ void TrtGptModelInflightBatching::reshapeKvTensors(OffsetTableDimensions const&
 using BlocksPerWindow = std::map<SizeType32, std::tuple<SizeType32, SizeType32>>;
 
 std::pair<BlocksPerWindow, std::vector<SizeType32>>
-TrtGptModelInflightBatching::clampWindowSizesToFitAtLeastOneSequence(BlocksPerWindow const& blocksPerWindow)
+TrtGptModelInflightBatching::clampWindowSizesToFitAtLeastOneSequence(
+    BlocksPerWindow const& blocksPerWindow, bool const failFastOnAttentionWindowTooLarge)
 {
     // At this point, we can only validate that the cheapest sequence in terms of kv-cache resources still fits. More
     // validation is needed on a per-request basis, once the prompt / output lengths and the actual beam width are
@@ -591,6 +592,16 @@ TrtGptModelInflightBatching::clampWindowSizesToFitAtLeastOneSequence(BlocksPerWi
     }
     TLLM_LOG_WARNING("maxAttentionWindowVec too large to fit at least one sequence in kvCache. Old: %s, New: %s",
         common::vec2str(getMaxAttentionWindowVec()).c_str(), common::vec2str(newMaxAttentionWindowVec).c_str());
+
+    if (failFastOnAttentionWindowTooLarge)
+    {
+        throw std::runtime_error(
+            "Attention window too large to fit even a single sequence in the KV cache. Failing fast rather than "
+            "attempting an adjustment of the window sizes. "
+            "Old: "
+            + common::vec2str(getMaxAttentionWindowVec()) + ", New: " + common::vec2str(newMaxAttentionWindowVec));
+    }
+
     setMaxAttentionWindowVec(newMaxAttentionWindowVec);
     if (getMaxSequenceLen() > getMaxAttentionWindow())
     {
@@ -613,7 +624,7 @@ TrtGptModelInflightBatching::clampWindowSizesToFitAtLeastOneSequence(BlocksPerWi
 
 std::unique_ptr<kv_cache_manager::KVCacheManager> TrtGptModelInflightBatching::createKvCacheManager(
     KvCacheConfig const& kvCacheConfig, KvCacheType kvCacheType, uint64_t freePrimaryMemBytes,
-    uint64_t freeSecondaryMemBytes, size_t extraCostMemory)
+    uint64_t freeSecondaryMemBytes, size_t extraCostMemory, bool const failFastOnAttentionWindowTooLarge)
 {
     TLLM_LOG_TRACE("%s start", __PRETTY_FUNCTION__);
     bool isCrossAttention = kvCacheType == KvCacheType::kCROSS;
@@ -657,7 +668,8 @@ std::unique_ptr<kv_cache_manager::KVCacheManager> TrtGptModelInflightBatching::c
     // and user also didn't provide maxAttentionWindow, which leads it to be equal to maxSeqLen
     if (kvCacheType == KvCacheType::kSELF)
     {
-        std::tie(blocksPerWindow, maxAttentionWindowVec) = clampWindowSizesToFitAtLeastOneSequence(blocksPerWindow);
+        std::tie(blocksPerWindow, maxAttentionWindowVec)
+            = clampWindowSizesToFitAtLeastOneSequence(blocksPerWindow, failFastOnAttentionWindowTooLarge);
     }
 
     kv_cache_manager::TempAttentionWindowInputs tempAttentionWindowInputs;

cpp/tensorrt_llm/batch_manager/trtGptModelInflightBatching.h

@@ -280,7 +280,8 @@ class TrtGptModelInflightBatching : public TrtGptModel
     void createBuffers(executor::DecodingConfig const& decodingConfig,
         std::optional<std::vector<executor::AdditionalModelOutput>> const& additionalModelOutputs);
     std::unique_ptr<KVCacheManager> createKvCacheManager(KvCacheConfig const& kvCacheConfig, KvCacheType kvCacheType,
-        uint64_t freePrimaryMemBytes, uint64_t freeSecondaryMemBytes, size_t extraCostMemory);
+        uint64_t freePrimaryMemBytes, uint64_t freeSecondaryMemBytes, size_t extraCostMemory,
+        bool const failFastOnAttentionWindowTooLarge = false);
     void createRnnStateManager();
     void createCustomAllReduceWorkspace();
     void createRuntimePerfKnobsTensor(executor::ExtendedRuntimePerfKnobConfig const& extendedRuntimePerfKnobConfig);
@@ -378,9 +379,11 @@ class TrtGptModelInflightBatching : public TrtGptModel
     /// window.
     ///
     /// @param blocksPerWindow map of window size to number of blocks.
+    /// @param failFastOnAttentionWindowTooLarge if true, the function will report a runtime error if the attention
+    /// window is too large to fit even a single sequence in the KV cache.
     /// @return pair of new blocks per window and new maxAttentionWindowVec
     [[nodiscard]] std::pair<BlocksPerWindow, std::vector<SizeType32>> clampWindowSizesToFitAtLeastOneSequence(
-        BlocksPerWindow const& blocksPerWindow);
+        BlocksPerWindow const& blocksPerWindow, bool const failFastOnAttentionWindowTooLarge = false);
 
     /// @brief Change the speculative decoding mode.
     void changeSpecDecMode(ScheduledRequests const& scheduledRequests);

cpp/tensorrt_llm/executor/executorConfig.cpp

@@ -34,7 +34,7 @@ ExecutorConfig::ExecutorConfig(SizeType32 maxBeamWidth, SchedulerConfig schedule
     std::optional<SpeculativeDecodingConfig> specDecConfig, std::optional<GuidedDecodingConfig> guidedDecodingConfig,
     std::optional<std::vector<AdditionalModelOutput>> additionalModelOutputs,
     std::optional<CacheTransceiverConfig> cacheTransceiverConfig, bool gatherGenerationLogits,
-    bool promptTableOffloading, bool enableTrtOverlap)
+    bool promptTableOffloading, bool enableTrtOverlap, bool failFastOnAttentionWindowTooLarge)
     : mMaxBeamWidth(maxBeamWidth)
     , mSchedulerConfig(std::move(schedulerConfig))
     , mKvCacheConfig(std::move(kvCacheConfig))
@@ -63,6 +63,7 @@ ExecutorConfig::ExecutorConfig(SizeType32 maxBeamWidth, SchedulerConfig schedule
     , mGatherGenerationLogits(gatherGenerationLogits)
     , mPromptTableOffloading(promptTableOffloading)
     , mEnableTrtOverlap(enableTrtOverlap)
+    , mFailFastOnAttentionWindowTooLarge(failFastOnAttentionWindowTooLarge)
 {
     TLLM_CHECK(iterStatsMaxIterations >= 0);
     TLLM_CHECK(requestStatsMaxIterations >= 0);
@@ -222,6 +223,11 @@ bool ExecutorConfig::getEnableTrtOverlap() const
     return mEnableTrtOverlap;
 }
 
+bool ExecutorConfig::getFailFastOnAttentionWindowTooLarge() const
+{
+    return mFailFastOnAttentionWindowTooLarge;
+}
+
 // setters
 
 void ExecutorConfig::setMaxBeamWidth(SizeType32 maxBeamWidth)
@@ -371,4 +377,9 @@ void ExecutorConfig::setEnableTrtOverlap(bool enableTrtOverlap)
     mEnableTrtOverlap = enableTrtOverlap;
 }
 
+void ExecutorConfig::setFailFastOnAttentionWindowTooLarge(bool failFastOnAttentionWindowTooLarge)
+{
+    mFailFastOnAttentionWindowTooLarge = failFastOnAttentionWindowTooLarge;
+}
+
 } // namespace tensorrt_llm::executor

cpp/tensorrt_llm/pybind/executor/executorConfig.cpp

@@ -459,7 +459,7 @@ void initConfigBindings(pybind11::module_& m)
             c.getExtendedRuntimePerfKnobConfig(), c.getDebugConfig(), c.getRecvPollPeriodMs(),
             c.getMaxSeqIdleMicroseconds(), c.getSpecDecConfig(), c.getGuidedDecodingConfig(),
             c.getAdditionalModelOutputs(), c.getCacheTransceiverConfig(), c.getGatherGenerationLogits(),
-            c.getPromptTableOffloading(), c.getEnableTrtOverlap());
+            c.getPromptTableOffloading(), c.getEnableTrtOverlap(), c.getFailFastOnAttentionWindowTooLarge());
         auto pickle_tuple = py::make_tuple(cpp_states, py::getattr(self, "__dict__"));
         return pickle_tuple;
     };
@@ -472,7 +472,7 @@ void initConfigBindings(pybind11::module_& m)
 
         // Restore C++ data
         auto cpp_states = state[0].cast<py::tuple>();
-        if (cpp_states.size() != 28)
+        if (cpp_states.size() != 29)
         {
             throw std::runtime_error("Invalid cpp_states!");
         }
@@ -505,7 +505,8 @@ void initConfigBindings(pybind11::module_& m)
             cpp_states[24].cast<std::optional<tle::CacheTransceiverConfig>>(),             // CacheTransceiverConfig
             cpp_states[25].cast<bool>(),                                                   // GatherGenerationLogits
             cpp_states[26].cast<bool>(),                                                   // PromptTableOffloading
-            cpp_states[27].cast<bool>()                                                    // EnableTrtOverlap
+            cpp_states[27].cast<bool>(),                                                   // EnableTrtOverlap
+            cpp_states[28].cast<bool>() // FailFastOnAttentionWindowTooLarge
         );
 
         auto py_state = state[1].cast<py::dict>();
@@ -542,7 +543,8 @@ void initConfigBindings(pybind11::module_& m)
                  std::optional<tle::CacheTransceiverConfig>,             // CacheTransceiverConfig
                  bool,                                                   // GatherGenerationLogits
                  bool,                                                   // PromptTableOffloading
-                 bool                                                    // EnableTrtOverlap
+                 bool,                                                   // EnableTrtOverlap
+                 bool                                                    // FailFastOnAttentionWindowTooLarge
                  >(),
             py::arg("max_beam_width") = 1, py::arg_v("scheduler_config", tle::SchedulerConfig(), "SchedulerConfig()"),
             py::arg_v("kv_cache_config", tle::KvCacheConfig(), "KvCacheConfig()"),
@@ -563,7 +565,7 @@ void initConfigBindings(pybind11::module_& m)
             py::arg("spec_dec_config") = py::none(), py::arg("guided_decoding_config") = py::none(),
             py::arg("additional_model_outputs") = py::none(), py::arg("cache_transceiver_config") = py::none(),
             py::arg("gather_generation_logits") = false, py::arg("mm_embedding_offloading") = false,
-            py::arg("enable_trt_overlap") = false)
+            py::arg("enable_trt_overlap") = false, py::arg("fail_fast_on_attention_window_too_large") = false)
         .def_property("max_beam_width", &tle::ExecutorConfig::getMaxBeamWidth, &tle::ExecutorConfig::setMaxBeamWidth)
         .def_property("max_batch_size", &tle::ExecutorConfig::getMaxBatchSize, &tle::ExecutorConfig::setMaxBatchSize)
         .def_property("max_num_tokens", &tle::ExecutorConfig::getMaxNumTokens, &tle::ExecutorConfig::setMaxNumTokens)
@@ -613,6 +615,9 @@ void initConfigBindings(pybind11::module_& m)
             &tle::ExecutorConfig::setPromptTableOffloading)
         .def_property(
             "enable_trt_overlap", &tle::ExecutorConfig::getEnableTrtOverlap, &tle::ExecutorConfig::setEnableTrtOverlap)
+        .def_property("fail_fast_on_attention_window_too_large",
+            &tle::ExecutorConfig::getFailFastOnAttentionWindowTooLarge,
+            &tle::ExecutorConfig::setFailFastOnAttentionWindowTooLarge)
         .def(py::pickle(executorConfigGetState, executorConfigSetState));
 }
 

examples/run.py

@@ -106,6 +106,13 @@ def parse_arguments(args=None):
         default=False,
         action='store_true',
         help="Run several 10 iterations to profile the inference latencies.")
+    parser.add_argument(
+        '--fail_fast_on_attention_window_too_large',
+        action='store_true',
+        default=False,
+        help=
+        'Exit with runtime error when attention window is too large to fit even a single sequence in the KV cache.'
+    )
 
     parser = add_common_args(parser)
 
@@ -455,6 +462,8 @@ def main(args):
             gpu_weights_percent=args.gpu_weights_percent,
             max_output_len=args.max_output_len,
             enable_context_fmha_fp32_acc=args.enable_context_fmha_fp32_acc,
+            fail_fast_on_attention_window_too_large=args.
+            fail_fast_on_attention_window_too_large,
         )
         if args.medusa_choices is not None:
             args.medusa_choices = ast.literal_eval(args.medusa_choices)
@@ -549,6 +558,8 @@ def main(args):
                 eagle_choices=args.eagle_choices,
                 return_all_generated_tokens=args.return_all_generated_tokens,
                 input_token_extra_ids=input_token_extra_ids,
+                fail_fast_on_attention_window_too_large=args.
+                fail_fast_on_attention_window_too_large,
                 language_adapter_uids=args.language_task_uids)
             torch.cuda.synchronize()
 
@@ -680,7 +691,9 @@ def main(args):
                     return_dict=True,
                     return_all_generated_tokens=args.
                     return_all_generated_tokens,
-                    input_token_extra_ids=input_token_extra_ids)
+                    input_token_extra_ids=input_token_extra_ids,
+                    fail_fast_on_attention_window_too_large=args.
+                    fail_fast_on_attention_window_too_large)
                 torch.cuda.synchronize()
         tensorrt_llm.profiler.stop("tmp")