On Fri 12-04-13 14:38:00, Ivan Danov wrote: > On 12/04/13 13:11, Michal Hocko wrote: > >On Fri 12-04-13 12:49:30, Ivan Danov wrote: > >>$ cat /proc/sys/vm/swappiness > >>60 > >OK, thanks for confirming this. It is really strange that we do not swap > >almost at all, then. > >>I have increased my swap partition from nearly 2GB to around 16GB, > >>but the problem remains. > >Increasing the swap partition will not help much as it almost unused > >with 2G already (at least last data shown that). > > > >>Here I attach the logs for the larger swap partition. I use a MATLAB > >>script to simulate the problem, but it also works in Octave: > >>X = ones(100000,10000); > >AFAIU this will create a matrix with 10^9 elements and initialize them > >to 1. I am not familiar with octave but do you happen to know what is > >the data type used for the element? 8B? It would be also interesting to > >know how is the matrix organized and initialized. Does it fit into > >memory at all? > Yes, 8B each, so it will be almost 8GB and it should fit into the > memory. It won't fit in because kernel and other processes consume some memory as well. So you have to swap. > I don't know details how it actually works, but if it cannot > create the matrix, MATLAB complains about that. Since it starts > complaining even after 2000 more in the second dimension, maybe it > needs the RAM to create it all. However on the desktop machine, both > RAM and swap are being used (quite a lot of them both). How much you swap depends on vm.swappiness. I would suggest increasing the value if your workload is really so anononymous memory based. Otherwise a lot of file pages are reclaimed which can lead to problems you are seeing. > >>I have tried to simulate the problem on a desktop installation with > >>4GB of RAM, 10GB of swap partition, installed Ubuntu Lucid and then > >>upgraded to 12.04, the problem isn't there, but the input is still > >>quite choppy during the load. After the script finishes, everything > >>looks fine. For the desktop installation the hard drive is not an > >>SSD hard drive. > >What is the kernel version used here? > $ uname -a > Linux ivan 3.2.0-40-generic #64-Ubuntu SMP Mon Mar 25 21:22:10 UTC > 2013 x86_64 x86_64 x86_64 GNU/Linux Is there any chance you could test with the latest vanilla kernel and Mel's patches from https://lkml.org/lkml/2013/4/11/516 on top? [...] -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>