I'm running a Linux netbook with an SSD. Since the SSD is slow (and I don't want to wear it out) I've been running without swap. So far this has been great, but I recently put a new kernel on (2.6.37) and noticed some slowdown. During this the disk drive light on my netbook stays on. LatencyTOP is only partially helpful in this, while one 3s (that's seconds not ms) delay is for 'disk write (synchronous),' one is 2s for 'page fault.' I don't understand why there would be much of a penalty for a page fault at all since I'm not using swap to begin with (and seem to have a lot of free/cached memory). What could be the cause of this, and is there a way to resolve it? Is such a high latency for page faults even harmful or is the problem elsewhere?
migrated from serverfault.com Feb 16 '11 at 22:52
Maybe the answers on this question may help you out. Page faults occur even on the absence of swap, when the program tries to access a part of the virtual memory that is mapped but not yet on the physical memory like data from an on-disk file. The correct term for that technique is Demand Paging.