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
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