On Fri, Sep 25, 2009 at 8:19 AM, Evan <eapa...@gmail.com> wrote: > On Fri, Sep 25, 2009 at 7:40 AM, Marius Gedminas <mar...@pov.lt> wrote: > >> On Fri, Sep 18, 2009 at 04:46:21AM -0700, J. Lennard wrote: >> > First I'm sorry to write what may appear as a rant, but I hope it is >> > not considered so. I'm writing to express huge instability problems in >> > Ubuntu 9.04. I migrated from ubuntu 8.04 (386) to ubuntu 9.04 (amd64) >> > using a simple clean install. >> ... >> > I don't really know where to start. During past month, my machine >> > constantly went to trashing mode where the hard-disk light is >> > constantly on and I can't access anything or even swtich to linux >> > console for several *minutes*. This has occured more than four times >> > although all I usually run is a pdf viewer, an mp3 player, emacs, and >> > firefox with simple html pages (not even gmail, flash, etc). >> >> Do you have any swap space? >> >> I've got an Asus EeePC 900 with 1 GB of RAM. Twice now I've experienced >> the same thing: constant disk I/O, huge latencies for any desktop task >> (switching windows, launching terminals). I suspect a bug in the Linux >> VM subsystem, since *I was not running out of memory*. Usually about >> 40-50% of my RAM is in disk cache---I keep track of memory usage via a >> GNOME panel applet. On those occasions cache size was shrinking, >> completely free memory was increasing, all application pages were being >> constantly swapped out and back in causing constant disk I/O (which is >> painful on an SSD). The fix was to create a temporary swap file in >> /tmp: >> >> sudo -s >> dd if=/dev/zero of=/tmp/swapfile bs=1M count=1024 >> mkswap /tmp/swapfile >> swapon /tmp/swapfile >> >> Instantly the system became responsible again, after using ~400 >> *kilobytes* of swap. >> >> I can only assume that having 0 swap space confused the VM somehow and >> kicked it into a full-on panic "let's free all the ram we can" mode. >> >> This swap file disappears after a reboot, and so far the problem hasn't >> recurred, so I didn't bother setting up a permanent swap partition (I'm >> afraid to destroy my SSD too quickly with constant writes---this already >> happened once thanks to ext3's journal). >> > > I have had this occur several times to me on a quad-core with 3GB ram (and > 6GB swap), but only ever when resuming. If I suspend with all free memory > used by cache (according to the Gnome panel applet), then occasionally on > resume it spends ~5minutes unresponsive with massive disk IO before coming > up. When it does come back everything is fine, except that all of that space > which was cache is now completely empty. I set my vm.swappiness value to 0 > (because I so rarely need it), so while I'm definitely not running out of > swap space, I can see how swappiness=0 might cause the same sort of effect. > I haven't found anything odd in the logs so I never filed a bug, but if it's > happening to other people in other situations this bears investigating. I > will open a bug on this as soon as I have time. >
This bug finally reoccurred, and I caught something in the log files this time. The bug is at https://bugs.launchpad.net/ubuntu/+source/pm-utils/+bug/438889 Mine appears to be in pm-utils, so I doubt it's the same as yours Marius, but it may be a more fundamental problem with the kernel's memory management. It's worth taking a look at in any case. Evan
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