ROCm/AITER: DeepSeek-R1 Issue On MI300X

Understanding the Deepseek-R1 Issue on MI300X with ROCm and AITER

Hey guys, let's dive into a tricky issue encountered while running Deepseek-R1 on vllm using ROCm and AITER, specifically on MI300X hardware. The core problem stems from how the AITER_ENABLE_VSKIP variable is handled. When this variable isn't explicitly set, it defaults to true. This seemingly innocuous default leads to significant problems during the execution of Deepseek-R1, resulting in memory-related errors that halt the process. Understanding the root cause and potential solutions is crucial for anyone working with these technologies. This article aims to explain the problem, its symptoms, and the steps to reproduce it, providing a comprehensive overview for developers and engineers facing similar challenges.

When we talk about AITER_ENABLE_VSKIP, we're referring to a configuration option that likely controls whether or not a specific optimization or code path is enabled within the AITER library. In this case, it appears that when VSKIP is enabled by default, it introduces an incompatibility or bug that surfaces when running Deepseek-R1 on the MI300X. This is further compounded by the fact that the error manifests as a memory aperture violation, which indicates that the kernel is attempting to access memory locations that are outside the permitted range. This could be due to incorrect address calculations, buffer overflows, or other memory management issues within the AITER library itself. The error messages provided in the issue report clearly point to this memory access problem, highlighting the specific kernel and memory addresses involved. Therefore, a deeper investigation into the memory access patterns of the AITER library when VSKIP is enabled is warranted to identify and resolve the underlying cause.

The significance of this issue is amplified by the increasing adoption of ROCm and AITER for accelerating deep learning workloads on AMD hardware. As more developers and organizations leverage these technologies, encountering and resolving such issues becomes paramount for ensuring stable and efficient performance. The fact that this problem specifically affects the MI300X hardware suggests that there might be unique characteristics or configurations of this hardware that exacerbate the issue. This could be related to memory architecture, caching mechanisms, or other hardware-specific features. Addressing this problem not only benefits users of Deepseek-R1 but also contributes to the overall robustness and reliability of the ROCm and AITER ecosystems. Further research and testing across different hardware platforms and software configurations are essential to identify and prevent similar issues from arising in the future.

Decoding the Error Details

The error messages provide critical clues about what's going wrong. Let's break down the key parts:

• HSA_STATUS_ERROR_MEMORY_APERTURE_VIOLATION: This is a clear indicator of a memory access problem. It means the GPU tried to access memory it shouldn't have.
• Kernel Name: _ZN5aiter50fmoe_bf16_blockscaleFp8_g1u1_vs_silu_1tg_ps_32x256E: This tells us the specific AITER kernel that's crashing. The vs in the name likely relates to the VSKIP option we discussed earlier.
• grid=[77824, 1, 1], workgroup=[256, 1, 1]: These are the dimensions of the kernel execution, showing how the work is divided across the GPU.
• /app/upstreambugfix/aiter20251007/aiter/jit/build/module_moe_asm/build/srcs/asm_fmoe.hip:250 fail to call hipModuleLaunchKernel: This pinpoints the exact line of code where the kernel launch fails, giving developers a precise location to investigate.
• Error code 700: hipErrorInvalidDeviceFunction

These error details collectively suggest that the AITER kernel, when compiled with VSKIP enabled, generates code that attempts to access invalid memory regions on the MI300X. The specific kernel name and line number provide valuable starting points for debugging and identifying the root cause of the memory violation.

The Kernel Signature Shift

Interestingly, older AITER commits (like 6b586ae) show a different kernel signature on MI300X: _ZN5aiter52fmoe_bf16_blockscaleFp8_g1u1_novs_silu_1tg_ps_32x256E. Notice the novs instead of vs? This suggests that in earlier versions, VSKIP was explicitly disabled, and the code path was different. The change in kernel signature indicates a deliberate modification in how the kernel is compiled or dispatched, potentially related to the introduction or modification of the VSKIP feature. This discrepancy between the older and newer versions of AITER highlights the importance of version control and careful examination of code changes when troubleshooting issues. It also suggests that the VSKIP feature might not be fully compatible with the MI300X architecture, or that there might be a bug in the way it's implemented.

The fact that the older commits used a kernel with novs (presumably meaning "no VSKIP") further strengthens the hypothesis that the VSKIP option is the culprit. It implies that the code path without VSKIP was stable and didn't exhibit the same memory access violations. This information is crucial for developers as it provides a potential workaround: explicitly disabling VSKIP or reverting to an older AITER commit might alleviate the issue. However, it's important to note that disabling VSKIP might also impact performance, so a careful evaluation of the trade-offs is necessary. Ultimately, the ideal solution would be to identify and fix the underlying bug in the VSKIP code path to ensure compatibility and optimal performance on MI300X.

Moreover, the contrast in kernel signatures raises questions about the intended behavior of the VSKIP option. Was it designed to be automatically enabled or disabled based on the hardware architecture? Or is it meant to be a user-configurable option? Understanding the design intent behind VSKIP is essential for determining the correct way to use it and for diagnosing any potential misconfigurations. If VSKIP is intended to be hardware-adaptive, then there might be a flaw in the detection logic that incorrectly enables it on MI300X. On the other hand, if it's a user-configurable option, then the documentation should clearly state its implications and provide guidance on when to enable or disable it.

MI308's Different Path

Adding another layer of complexity, the issue report mentions that on MI308, a different kernel is called: _ZN5aiter59fmoe_stage1_bf16_pertokenFp8_blockscale_g1u1_64x128_2tg_pf3E. This indicates that AITER might be using different code paths or optimizations based on the specific GPU architecture. This difference in kernel execution paths between MI300X and MI308 suggests that the AITER library employs a dynamic dispatch mechanism, where the appropriate kernel is selected based on the detected hardware capabilities. This approach is common in high-performance computing libraries to ensure optimal performance across diverse hardware platforms. However, it also introduces the possibility of bugs or inconsistencies if the dispatch logic is not correctly implemented or if the hardware detection is flawed.

The use of different kernels on MI300X and MI308 could be due to variations in memory architecture, compute capabilities, or other hardware-specific features. For example, MI308 might have a different cache hierarchy or a more efficient memory controller that allows it to benefit from a different kernel implementation. Alternatively, the MI300X might have certain limitations or constraints that necessitate the use of a different kernel. Understanding the specific reasons behind these kernel variations requires a deep understanding of the hardware architectures and the optimization strategies employed by the AITER library.

Furthermore, the fact that MI308 doesn't exhibit the same memory access violations as MI300X suggests that the kernel used on MI308 might be more robust or better suited for the hardware. This could be due to differences in the way memory is accessed, or in the algorithms used to perform the computation. Comparing the code of the two kernels could provide valuable insights into the root cause of the issue on MI300X. It might reveal specific memory access patterns or algorithmic choices that contribute to the memory violation. Therefore, a detailed code analysis, combined with hardware performance profiling, is essential for identifying and resolving the problem.

Proposed Solution: #1136

The issue report references a proposed solution in pull request #1136. This is likely the most promising avenue for resolving the problem. By examining the changes introduced in that pull request, developers can gain a better understanding of how the issue is being addressed and whether it's likely to fix their specific problem. Pull request #1136 likely contains code modifications that aim to address the memory access violation or the incorrect VSKIP handling on MI300X. These modifications could involve changes to the kernel code, the dispatch logic, or the configuration options related to VSKIP.

By carefully reviewing the code changes, developers can assess their impact and determine whether they are likely to resolve the issue. It's also important to consider whether the changes introduce any new problems or side effects. For example, the fix might improve stability on MI300X but degrade performance on other hardware platforms. Therefore, thorough testing and benchmarking are necessary to ensure that the solution is both correct and efficient.

In addition to reviewing the code changes, it's also helpful to examine the discussion and comments associated with the pull request. These discussions often provide valuable context and insights into the reasoning behind the changes. They might also reveal alternative approaches or potential limitations of the proposed solution. By actively participating in the discussion and providing feedback, developers can contribute to the development of a robust and reliable solution.

Steps to Reproduce

The issue report provides detailed steps to reproduce the error, which is invaluable for debugging and testing. These steps involve:

1. Setting up a container: This ensures a consistent and isolated environment.
2. Installing vllm and aiter: This ensures you have the necessary software components.
3. Serving Deepseek-R1 with specific parameters: This triggers the problematic code path.

By following these steps, developers can reliably reproduce the error on their own systems, allowing them to experiment with different solutions and verify their effectiveness. The use of a container ensures that the environment is consistent across different machines, eliminating potential variations that could complicate the debugging process. The specific parameters used to serve Deepseek-R1, such as the tensor parallel size and block size, might be crucial for triggering the issue. Therefore, it's important to use the exact same parameters as specified in the issue report.

Moreover, the logging configuration (> logs/server.log 2>&1) ensures that all relevant error messages and debugging information are captured for analysis. This can be extremely helpful for identifying the root cause of the problem and for tracking the progress of the debugging effort. By examining the logs, developers can gain insights into the sequence of events that lead to the error, and they can identify any specific function calls or memory accesses that are causing the violation.

In summary, the detailed steps to reproduce the error provide a solid foundation for debugging and testing. By following these steps carefully and analyzing the resulting logs, developers can effectively investigate the issue and develop a reliable solution.

Key Takeaways and Next Steps

Alright guys, this detailed issue report gives us a solid foundation for tackling this problem. Here's what we've learned:

• The AITER_ENABLE_VSKIP setting seems to be the key trigger.
• The error is a memory access violation during kernel execution.
• MI300X behaves differently than MI308.
• Pull request #1136 might hold the solution.

Next steps would involve:

1. Examining pull request #1136: Understand the proposed changes and their impact.
2. Trying to reproduce the error: Verify that the steps in the report consistently trigger the issue.
3. Testing the solution from #1136: See if it resolves the problem without introducing new ones.
4. Diving deeper into the AITER code: Investigate the memory access patterns and the VSKIP logic.

By working together and systematically investigating these areas, we can hopefully get Deepseek-R1 running smoothly on MI300X with ROCm and AITER.

For more information on ROCm and AITER, check out the official ROCm Documentation. Good luck!