Messages in this thread | | | Date | Fri, 23 Jan 2015 17:18:04 -0500 | From | John Moser <> | Subject | OOM at low page cache? |
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Why is there no tunable to OOM at low page cache?
I have no swap configured. I have 16GB RAM. If Chrome or Gimp or some other stupid program goes off the deep end and eats up my RAM, I hit some 15.5GB or 15.75GB usage and stay there for about 40 minutes. Every time the program tries to do something to eat more RAM, it cranks disk hard; the disk starts thrashing, the mouse pointer stops moving, and nothing goes on. It's like swapping like crazy, except you're reading library files instead of paged anonymous RAM.
If only I could tell the system to OOM kill at 512MB or 1GB or 95% non-evictable RAM, it would recover on its own. As-is, I need to wait or trigger the OOM killer by sysrq.
Am I just the only person in the world who's ever had that problem? Or is it a matter of questions fast popping up when you try to do this *and* enable paging to disk? (In my experience, that's a matter of too much swap space: if you have 16GB RAM and your computer dies at 15.25GB usage, your swap space should be no larger than 750MB plus inactive working RAM; obviously, your computer can't handle paging 750MB back and forth. If you make it 8GB wide and you start swap thrashing at 2GB usage, you have too much swap available).
I guess you could try to detect excessive swap and page cache thrashing, but that's complex; if anyone really wanted to do that, it would be done by now. A low-barrier OOM is much simpler.
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