Ubuntu – Nasty CPU spikes that aren’t connected to any visible processes

cpu loadkernelnvidia

Really strange issue here. I intermittently keep getting really unpleasant CPU spikes, where the CPU gets to 80-90% busy across all cores for about 5 minutes. When I look at conky, in htop or system monitor, and sort by % CPU, I can't see any process that accounts for this much CPU usage.

The only things I've changed since this started are:

  • I moved to kernel version 2.6.35 (home compiled, up from 2.6.24-1)
  • I installed the Nvidia driver 256.44 (up from 256.34)

Now, I am willing to downgrade either/both of those to find the problem but I'd prefer to do this as scientifically as possible and find out what is causing the CPU explosion before I downgrade.

Edit: My precise issue looks like a nvidia regression in their latest driver. Other people are getting similar spikes.

Best Answer

It might be a kernel thread, those are hidden by default in most performance monitors. In htop you can hide/show kernel threads with "K" (shift+k).

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