On Sun, Dec 12, 2010 at 6:43 AM, Ted Ts'o <ty...@mit.edu> wrote: > On Sun, Dec 12, 2010 at 04:18:29AM -0600, Jon Nelson wrote: >> > I have one CPU configured in the environment, 512MB of memory. >> > I have not done any memory-constriction tests whatsoever. > > I've finally been able to reproduce it myself, on real hardware. SMP > is not necessary to reproduce it, although having more than one CPU > doesn't hurt. What I did need to do (on real hardware with 4 gigs of > memory) was to turn off swap and pin enough memory so that free memory > was around 200megs or so before the start of the test. (This is the > natural amount of free memory that the system would try to reach, > since 200 megs is about 5% of 4 gigs.) > > Then, during the test, free memory would drop to 50-70 megabytes, > forcing writeback to run, and then I could trigger it about 1-2 times > out of three. > > I'm guessing that when you used 512mb of memory, that was in effect a > memory-constriction test, and if you were to push the memory down a > little further, it might reproduce even more quickly. My next step is > to try to reproduce this in a VM, and then I can start probing to see > what might be going on.
I'm glad you've been able to reproduce the problem! If you should need any further assistance, please do not hesitate to ask. -- Jon -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
