Memory Failure

I did some overclocking (to 4.2 GHZ) and gave the CPU and memory a trial using Prime95 and other torture tests. Later, much later, I realised that part of my memory was gone!

Checking the BIOS showed memory failures of two of 8 modules, reducing my total to 24GB. I’m not sure it was the overclocking, the torture tests or simply old age (the PC and memory is 6 years old). The funny thing was that I could boot into Linux and run some applications, and whenever I used Firefox I would sooner or later get a freeze. I monitored the processes and saw that the kswapd demon was busy. It took me a little to grasp that I had “lost” memory.

My originally 32GB PC memory was divided as follows at boot:

  • 20GByte for Windows
  • 2GByte for hugepage tables etc. (that is a lot, but I wanted to be on the save side)
  • The rest (10GByte) for Linux

Since I allocated 22GByte to hugepages at boot, my Linux host had only 2GByte memory when 8GByte of RAM went bad.

Usually 2GByte would be enough for a Linux Mint Mate host, but having dozens of tabs in Firefox eventually exceeded the available memory. I had reduced my swappiness  value to a minimum, which was great with lots of memory. But 2GByte is a little low.

It’s difficult to find the same memory I bought 6 years ago, so instead of paying hundreds of dollars for replacing the entire PC memory, I decided to downsize to 24GByte altogether – 16GByte to Windows, around 1 GByte to hugepages page tables, and the rest to Linux. The system works fine and I believe I can use that PC for another 2 years for photo editing in a Windows VM, and general use under Linux.

Here is my basic configuration:

  • Intel i7 3930K CPU
  • Nvidia Quadro 2000 for the Linux host
  • Nvidia GTX 970 for the Windows VM
  • 24GByte RAM quad channel memory

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