Am 07.11.2013 17:28, schrieb sd: > Hi, > > Some details about zram-config: > > [ppp] 1. I have somehow the impression the system is not fully aware > about the memory assigned to zram. > [leszek] To 1. You are wrong. Its a normal swap and all apps which are > aware of swap are aware of zrams swap. > > @leszek - you are right, but that is not what I meant. I meant the > system is somehow not aware about the RAM amount being in use by zram > (the system sure knows about zram swap memory). > > Below are some tests I did (with a live Lubuntu 13.04 cd in virtual box): > > (fresh start) > > $sudo swapoff -a > $sudo service zram-config stop > $free -h > total used free > Mem: 994M 866M 127M > Swap:0B 0B 0B > > $sudo service zram-config start > $free -h > total used free > Mem: 994M 870M 123M > Swap:497M 0B 497M > > $cat /proc/swaps > ... Size > /dev/zram0 ... 254508 > /dev/zram0 ... 254508 > > So ~ 250M per each zram swap. > > Sure the system is aware of the zram swap, free command shows it - > this is obvious to me. > The system is, however, somehow not aware of the RAM amount zram is > using, atm it looks like it is using like 0B - may be zram allocates > the memory dynamically as needed (and the given amount is just a max > limit)? > > (install memtester)
I am not sure what memtester does and how it works exactly. > > $sudo memtester 512M > > works ok > > free -h (on new terminal tab) shows 80M free, no swap used > > stop memterster (Ctrl+C) > > $sudo memtester 1024M > > want 1024, got 1024 trying mlock ... > > System freezes, no chance to recover. You have to power the machine down. Does this also happen when you start applications and got to 1024 MB RAM usage ? > > (Reset VM with live CD) and next test: > > $sudo swapoff -a > $sudo service zram-config stop > $free -h > total used free > Mem: 994M 734M 259M > Swap:0B 0B 0B > > $sudo memtester 1024M > want 1024M, got 604M trying mlock ... > > The live CD shows next the lightdm login prompt here, not perfect, but > much better than the freeze with zram active. > The system behaves better in this case on low memory. At least you > have a chance to do a propert shutdown, start a new desktop session, etc. > > After restart of VM with live CD next test: > > $sudo swapoff -a > $sudo service zram-config stop > $sudo service zram-config start > $free -h > total used free > Mem: 994M 864M 129M > Swap:497M 0B 497M > > $sudo memtester 512M > want 512, got 512 locked > > $free -h (new terninal tab, while memtester command above active) > total used free > Mem: 994M 929M 64M > Swap:497M 4K 497M > > $top > memtester RES 512m VIRT 516m %MEM 51.5% > > Now in a new terminal tab: > > $sudo memtester 128M > want 128MB got 128 MB locked > > $free -h > similar to above 4M swap used > > $sudo memtester 512M (new terminal tab) > Same system freeze as before. > > The behavior what happens in a Lubuntu box when there is no more free > memory seems to be deterministic: > > -With zram swap active - it just freezes - no warning, no chance, you > have to reset power of the system. This should not be the case (at least when there is no other bug in the kernel) > -Without zram active - it kills the desktop user session, shows lighdm > login - much better. > The interesting question would be if someone could verify this with normal applications instead of memtester. -- Lubuntu-users mailing list Lubuntu-users@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/lubuntu-users
