On Fri, Sep 28, 2012 at 1:32 PM, Luigi Semenzato <semenzato@xxxxxxxxxx> wrote: > Greetings, > > We are experimenting with zram in Chrome OS. It works quite well > until the system runs out of memory, at which point it seems to hang, > but we suspect it is thrashing. Or spinning in some sad loop. Does the kernel have the CONFIG_DETECT_* options to figure out what is happening? Can you invoke the Alt-SysRQ when it is hung? > > Before the (apparent) hang, the OOM killer gets rid of a few > processes, but then the other processes gradually stop responding, > until the entire system becomes unresponsive. Does the OOM give you an idea what the memory state is? Can you actually provide the dmesg? > > I am wondering if anybody has run into this. Thanks! > > Luigi > > P.S. For those who wish to know more: > > 1. We use the min_filelist_kbytes patch > (http://lwn.net/Articles/412313/) (I am not sure if it made it into > the standard kernel) and set min_filelist_kbytes to 50Mb. (This may > not matter, as it's unlikely to make things worse.) > > 2. We swap only to compressed ram. The setup is very simple: > > echo ${ZRAM_SIZE_KB}000 >/sys/block/zram0/disksize || > logger -t "$UPSTART_JOB" "failed to set zram size" > mkswap /dev/zram0 || logger -t "$UPSTART_JOB" "mkswap /dev/zram0 failed" > swapon /dev/zram0 || logger -t "$UPSTART_JOB" "swapon /dev/zram0 failed" > > For ZRAM_SIZE_KB, we typically use 1.5 the size of RAM (which is 2 or > 4 Gb). The compression factor is about 3:1. The hangs happen for > quite a wide range of zram sizes. > > -- > 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> > -- 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>