GEEKOM A5 mini-PC Review: Affordable Cezanne Zen 3 at 35W

System Performance: Multi-Tasking

One of the key drivers of advancements in computing systems is multi-tasking. On mobile devices, this is quite lightweight - cases such as background email checks while the user is playing a mobile game are quite common. Towards optimizing user experience in those types of scenarios, mobile SoC manufacturers started integrating heterogenous CPU cores - some with high performance for demanding workloads, while others were frugal in terms of both power consumption / die area and performance. This trend is now slowly making its way into the desktop PC space.

Multi-tasking in typical PC usage is much more demanding compared to phones and tablets. Desktop OSes allow users to launch and utilize a large number of demanding programs simultaneously. Responsiveness is dictated largely by the OS scheduler allowing different tasks to move to the background. The processor is required to work closely with the OS thread scheduler to optimize performance in these cases. Keeping these aspects in mind, the evaluation of multi-tasking performance is an interesting subject to tackle.

We have augmented our systems benchmarking suite to quantitatively analyze the multi-tasking performance of various platforms. The evaluation involves triggering a ffmpeg transcoding task to transform 1716 3840x1714 frames encoded as a 24fps AVC video (Blender Project's 'Tears of Steel' 4K version) into a 1080p HEVC version in a loop. The transcoding rate is monitored continuously. One complete transcoding pass is allowed to complete before starting the first multi-tasking workload - the PCMark 10 Extended bench suite. A comparative view of the PCMark 10 scores for various scenarios is presented in the graphs below. Also available for concurrent viewing are scores in the normal case where the benchmark was processed without any concurrent load, and a graph presenting the loss in performance.

The addition of concurrent loading obviously reduces the PCMark 10 scores. The A5 doesn't lose out too much on the performance front despite the lack of a 'thread director' mechanism. This is due to the additional number of high-performance cores compared to the equivalent-generation Alder Lake-P processor. Other than that, the relative ordering across different processor generations is maintained.

Following the completion of the PCMark 10 benchmark, a short delay is introduced prior to the processing of Principled Technologies WebXPRT4 on MS Edge. Similar to the PCMark 10 results presentation, the graph below show the scores recorded with the transcoding load active. Available for comparison are the dedicated CPU power scores and a measure of the performance loss.

The A5 loses around half its performance in the presence of the transcoding task. However, the eight high-performance cores ensures that the system actually moves up in the raw scores front compared to the no-concurrent-loading scenario.

The final workload tested as part of the multitasking evaluation routine is CINEBENCH R23.

The performance loss in 3D rendering is around 50%, with the multi-threaded case being slightly less impacted. However, the relative ordering between the different systems doesn't change.

After the completion of all the workloads, we let the transcoding routine run to completion. The monitored transcoding rate throughout the above evaluation routine (in terms of frames per second) is graphed below.

The drop in transcoding frame rate is slightly higher for the AMD systems compared to the newer Intel systems with the thread director technology. The larger count of high-performance cores in the AMD systems helps alleviate some of the performance loss.