lubuntu-qa team mailing list archive

[Jörn Schönyan <joern.schoenyan@xxxxxx>]

Am 28.09.2013 11:31, schrieb Leszek Lesner:
> Am 28.09.2013 11:03, schrieb Jörn Schönyan:
> > There are freezes with ZRAM in Precise, too. I experience this both 
> > with original stack/kernel and the enablement stack from Raring. 
> > Sometimes while shutting down, sometimes after a long session or when 
> > the RAM is "full". After disabling ZRAM, there are no problems at all.
> As far as I know the Precise kernel is 3.2 so it should not be 
> affected by the problem currently introduced by the 3.10.6 kernel. The 
> same goes for raring which uses the 3.8 kernel. And I hope the ubuntu 
> kernel devs did not port over the broken zram module from 3.10.6 to 
> the raring kernel.
> So there only might be two possibilities:
> 1. Its another bug.
> 2. Its not really freezing but just writing a whole lot of chunks to 
> zram which causes the cpu to run at 100 % for a long time and making 
> system usage unusable until the chunk is written to zram.
I am not 100 percent sure, as it is not my own machine :-/ myself, I 
haven't seen the freezes.
> The second thing can happen when lots of memory needs to be compressed 
> into ram and the cpu is not the fastest (single core for example). So 
> basically more than 60% of ram needs to be compressed. This takes a 
> longer time then and maybe halt user input for the time being.
> So it would help if you could verify if thats the case for you and if 
> it still halts when you give it some time to work. (not more than 10 
> mins please :) If this is really the case there are ways to limit the 
> ram that is available for compression (so limit it to 40% for example) 
> or even tweak the swapping setting to set how big the chunks should be 
> that are written to swap. (swap in this case made available from zram)
The owner waited at least 5 minutes, if it will unfreeze. The notebook 
is quite old, a Pentium M if I remember correct. It has 512 MB RAM and a 
VIA graphics card which I first suspected to cause the freeze :-)
> Also in rare occoasions(so if you only have 1 GB RAM and zram only 
> gives you 250 MB of swapspace and you need more) it might be useful to 
> use zram in combination with swap space on harddrive. So it would than 
> first swap out to zram until its full and then write to swap on hd.
> As for the shutdown issue this is exactly where it might come to an 
> hold for some seconds as it needs to clean zram (swap space by zram is 
> basically unmounted and the contents is written back to ram by swapd 
> or at least it is trying to write as much as possible back to ram)
Could be - I've set up a swap partition with 1,5 GB so this should in 
theory not be an issue.

Jörn