To see the performance difference of running on GPU over CPU, manually switch where your queries are run:
- Enable timing reporting in
- Ensure that you are in GPU mode (the default):
- Run your queries a few times. Because data is lazily moved to the GPUs, the first time you query new data/columns takes a bit longer than subsequent times.
- Switch to CPU mode:
\cpuOr add the g_cpu_mode hint to the query and run your queries a few times.
- Compare the different runtimes.
If you are using a large data set, you should see a significant difference between the two. However, if the sample set is relatively small (for example, the sample 7-million flights dataset that comes preloaded in OmniSci), some of the fixed overhead of running on the GPUs causes those queries to appear to run slower than on the CPU.