A CPU-bound thread and an I/O bound thread competing (OS-X)

The following visualizations show thread scheduling when an I/O-bound thread must compete with a CPU-bound thread. In this test, the I/O bound thread receives and echos a series of infrequently sent UDP packets. Zoom into the green spikes to see how the interpreter switches from the CPU-bound thread to the I/O handler. It's not obvious from the initial picture, but you will see a big difference on multiple cores as you zoom in. You can also view a Linux version of this page.

OS-X, 1 I/O-Thread, 1 CPU-Thread, 1 CPU [ code ]

OS-X, 1 I/O-Thread, 1 CPU-Thread, 4 CPUs

Test Details

Tests were conducted on the following system:

• Python 2.6
• MacPro 2 x 2.66 Ghz Dual-Core Intel Xeon, 3GB 667 Mhz DDR2 FB-DIMM
• OS-X 10.6.2 (Snow Leopard)

Take Me To More Visualizations!

• Threads running on 1 CPU

• 2 CPU bound threads running on 1 and 2 CPUs

• 4 CPU bound threads running on 1, 2, and 4 CPUs

• A CPU-bound thread and an I/O bound thread on 1 and 2 CPUs

• 512 I/O bound threads running on 2 CPUs

• 512 I/O bound threads running on 1 CPU