Speculative decoding can improve vLLM throughput on AMD MI300X GPUs, but the gain depends on whether a draft method proposes tokens cheaply and accurately enough for the target model to accept them. AMD has reported results as high as 2.3× in one Llama example, while its other benchmarks show that gains change with batch size and execution mode. Those figures describe particular configurations—not a general MI300X speedup.
How speculative decoding works in vLLM
In ordinary autoregressive generation, a target model produces output one committed token at a time. Speculative decoding adds a draft component that proposes several candidate future tokens. The target model then checks those candidates in a verification pass. Candidates the target accepts can be committed together; if one is rejected, later candidates in that proposal are discarded and the target supplies the next token. The target model remains responsible for the output.
The potential benefit is fewer sequential target-model decode steps. The cost is the draft method’s own computation and memory use. A draft that is slow, or whose proposals the target often rejects, can consume resources without saving enough target-model work. vLLM’s report and AMD’s benchmarks both show why acceptance behavior and serving configuration matter alongside raw model speed.
What the MI300X measurements establish
The vLLM project’s August 23, 2026 report surveys five speculative-decoding methods and measurements on AMD GPUs. It covers selected Gemma, Qwen, MiniMax, and Kimi models, and says output-token throughput varies with the model, draft checkpoint, workload, proposal length, and serving configuration. The report includes MI300X and MI355X results, but its measurements should be read as configuration-specific evidence rather than a single speedup applicable to every MI300X deployment. Read the vLLM report.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Methods covered in the vLLM report
- Native MTP
- Gemma 4 MTP
- EAGLE-3
- DFlash
- DSpark
These are different drafting approaches, not interchangeable settings with guaranteed equal overhead or acceptance. The available report summary establishes that they were evaluated, but does not provide a common numerical speedup for each method on MI300X. A deployment decision therefore needs results for the specific target and draft checkpoints, workload, and serving setup under consideration.
Disclosed MI300X test platform
For its MI300X platform, the vLLM report lists eight MI300X GPUs (gfx942) and two AMD EPYC 9654 96-core processors. Its software stack was Ubuntu 22.04.5 LTS, ROCm/HIP runtime 7.2.53211, vLLM 0.23.1rc1.dev1120+g0f0f28b53, PyTorch 2.11.0+gitd0c8b1f, Transformers 5.13.1, and Python 3.12.13. The report cautions that server configuration, software, vLLM version, drivers, and optimizations can change performance. These details are part of the result: a different stack or GPU configuration is not a like-for-like reproduction.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
How to interpret AMD’s earlier speedup figures
AMD published earlier MI300X evidence using older software than the 2026 vLLM report. The figures below are useful examples of how results can vary, but they are not direct comparisons to the newer report because the tested setups and software versions differ.
| Evidence | Reported result | Scope and qualification |
|---|---|---|
| AMD ROCm speculative-decoding tutorial | Up to 2.3× faster | AMD’s example uses Llama-3.1 70B as the target and Llama-3.1 1B as the draft on MI300X with vLLM. The tutorial’s starting setup specifies Ubuntu 22.04, ROCm 6.2 or later, Docker, and Hugging Face access to the checkpoints. The figure is an upper result for that example, not a general MI300X expectation. AMD tutorial. |
| AMD ROCm blog, March 27, 2025 | 1.32×–2× in eager mode; 1.5×–2.9× in graph mode | These are throughput speedups across eight vLLM scenarios at batch size 1, measured with ROCm 6.2 and vLLM 0.6.2. The ranges are not a prediction for other batch sizes, models, or software. AMD benchmark blog. |
| AMD ROCm blog, larger-batch test | Speculative decoding slowed eager mode from batch size 8 onward and graph mode from batch size 32 | This test used PhindCodeLlama-v2-34B with TinyLlama-1.1B as draft and a draft length of 8. The observed transitions apply to this benchmark setup only; they are not universal batch-size cutoffs. AMD benchmark blog. |
The contrast between batch-size-1 gains and larger-batch slowdowns illustrates a central trade-off: draft-and-verify work may help when it removes enough serial target-model steps, but its overhead can outweigh that benefit in another operating regime. Eager and graph execution can also produce different outcomes, so results from one mode should not be used to predict the other.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Why results vary between methods and workloads
Draft cost and acceptance
A draft method must be inexpensive enough to offset its own compute and memory overhead. Its proposals must also match what the target can accept. A fast draft with poor acceptance may save little, while a more costly draft may still be beneficial if it enables enough tokens to be committed per verification pass. Measure both proposal behavior and end-to-end serving performance rather than treating proposal length alone as a measure of value.
Model pair, checkpoint, and task
The target model and draft checkpoint shape the work and the likelihood that proposed tokens are useful. A result for one pair—such as Llama-3.1 70B with Llama-3.1 1B—does not establish the result for another pair. Workload matters too: a benchmark’s prompts, requested output lengths, and generation settings affect the measured serving behavior.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Proposal length, batch size, and execution mode
Longer proposals can reduce the number of target verification steps when candidates are accepted, but also change the amount of draft and verification work. Batch size changes the balance between that extra work and the target model’s throughput. The 2025 AMD test demonstrates that batch-size behavior can differ between eager and graph execution; it does not identify a universal point at which speculative decoding stops helping.
Software and hardware configuration
GPU count and platform, ROCm and driver versions, vLLM and framework versions, and runtime optimizations all affect whether a benchmark can be reproduced. The older AMD results use ROCm 6.2 and vLLM 0.6.2, whereas the later vLLM MI300X report lists ROCm/HIP 7.2.53211 and a vLLM 0.23.1 development build. Treat these as separate software-era measurements, not a controlled before-and-after comparison.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
How to evaluate speculative decoding for your MI300X service
Compare baseline autoregressive serving with each candidate drafting method on the same target model, hardware, workload, configuration, and software stack. A practical evaluation should record:
- GPU model and count, host platform, ROCm and driver versions, and all relevant framework and vLLM versions.
- Target model and exact draft checkpoint, including the drafting method.
- Prompt workload, requested output length, sampling and generation settings, and serving configuration.
- Draft proposal length, acceptance behavior, and memory or other operational overhead.
- Batch size and execution mode, distinguishing eager from graph execution where applicable.
- Output-token throughput and latency, using the same measurement method for baseline and speculative runs.
Keep comparisons controlled: change the drafting method or a single serving variable at a time, and retain the same workload and target configuration. If the result is intended to guide production capacity or user experience, examine throughput and latency rather than relying on throughput alone. Report the tested setup next to any speedup so readers can tell what the number does—and does not—predict.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
