Mac Pro memory—stress testing

How to determine that the memory is reliable, even under stressful (hot) conditions? Run the diglloydTools run-stress-test command, designed to tax a Mac OS X system to its limits (excepting the video card).

The system needs memory to run of course, so diglloydTools can’t test all the memory. But that’s not critical for its intended purpose. For systems with more than 2GB of memory, running multiple copies of diglloydTools is the answer to stressing most of the memory. Test all but about 512MB; it is counterproductive to attempt to test all of it as this will provoke system “paging”, or swapping of memory contents back and forth from the hard disk.

With 10GB memory, running 4 copies of diglloydTools (in 4 Terminal windows), each with 2GB of memory (512MB per thread), is a good way to stress most of the memory in the system (8GB). (A fifth copy could be run to soak up another 1.5GB or so, or each of the four could test 2.4GB or so).

I used the following command in Terminal for each of the 4 copies:

nice dlt run-stress-test --num-threads 4 --memory-per-thread 512M --duration 4h

The 'nice' command tells the system to reduce the priority of the task. This allows other running programs to remain responsive even under heavy testing.

No ordinary use of the system could ever stress the system (and memory) nearly as much. Even under this incredible load, the fans run only slightly louder, even though all four CPU cores are running at 100% and accessing most of the system memory.