lubuntu-qa team mailing list archive

[JM <meets@xxxxxx>]

Hi,

About ZRAM : I have written a very detailed bug report last year about the chosen setups
in Ubuntu. (Which has not been considered and no argument given : removed! :-( )


* For one, in Live it is limited to machines which have less than 512 MB RAM. I consider
this is not relevant at all, from my own experience.
Therefore I did this in Ubuntu Openbox Remix:
http://meets.free.fr/Downloads/BentoVillageProject/Configurations/System/Zram/usr/share/initramfs-tools/hooks/compcache.patch

* For two, creating block devices which are as large as 50% of the available ram is twice
as large as what has been adviced by the author of the program, and indeed, if ZRAM
allows having an extra memory available, in Live, for install time particularly, when it
is very desirable, 50% may be a problem at some point when the CPU is an old one, for
compressing and decompressing needs CPU power.

Therefore in Ubuntu Openbox Remix:
http://meets.free.fr/Downloads/BentoVillageProject/Configurations/System/Zram/usr/share/initramfs-tools/conf.d/compcache.patch

:)

In Archlinux for the time being, I have 4 GB RAM and zram bloc devices which are 20% as
large as my available RAM:
with swap partition not mounted:

****
$ free
             total       used       free     shared    buffers     cached
Mem:       4052432    3910496     141936          0      11320    1951376
-/+ buffers/cache:    1947800    2104632
Swap:       810480          0     810480

****

You could wonder why I use zram in a machine having 4 GB ram : well I sometimes fire two
virtual box machines at same time to compare things in both, or a heavy distribution in
Virtualbox, and then it is useful.


* For three, I consider important having a sysctl file which tells the kernel not to swap
to disk, or the zram device is of no use:
http://meets.free.fr/Downloads/BentoVillageProject/Configurations/System/etc/sysctl.d/50-local.conf

(you can also notice the commented line for people using laptops)

Regards,
Mélodie



On Sat, 21 Sep 2013 23:19:37 +0100
Phill Whiteside <PhillW@xxxxxxxxxx> wrote:

> Hi Nio,
> 
> If the issues of zram cannot be fixed for our desktop installer, then there
> are also much more serious issues for zram and the kernel. If Jopseph
> cannot sort out the issue, I see little choice but to ask Julien to disable
> z-ram. That request would weigh very heavy on my heart, Kernel freeze is
> not just yet, so I am hopeful that the required patches can be pulled in.
> Yes, we may be sailing close to 'freeze', but it is a 'bug".
> 
> Regards,
> 
> Phill.
> 
> 
> On 21 September 2013 21:00, Nio Wiklund <nio.wiklund@xxxxxxxxx> wrote:
> 
> > Interesting pespective, Phill,
> >
> > I think we can live with the buggy combo  kernel 3.11 + zRAM, because
> > zRAM can be switched on and off by shell commands. So we can choose to
> > use it only to enable the lower RAM machines to install via desktop :-)
> > in the beginning (in the released 13.10 iso images).
> >
> > And then, when we are rather sure that the bugs are fixed, when can
> > supply an update, that will switch zRAM on also for the other cases
> > (running Lubuntu live and installed).
> >
> > Best regards
> > Nio
> >
> > On 2013-09-21 21:27, Phill Whiteside wrote:
> > > As zram is a part of the kernel and enabled by default, do not get crazy
> > > about it. I had this back with kvm (virt-manager) when the fix was
> > > pulled into the 'ubuntu' kernel from a fix in the Red Hat one. As it
> > > appears more clearly that zram has issues, it not only affects lubuntu
> > > and *buntu but quite possibly all of the *nix systems running 3.11. It's
> > > really bad timing for us on *buntu as it was not found by you guys until
> > > really late in the cycle. The 3.11 kernel arrived part way through and
> > > was accepted, I'm not 100% sure that 3.11 is totally stable, but it is
> > > what is going to be released with 13.10. For lubuntu, the loss of zram
> > > in the installer would be a blow, as we use it to enable the lower RAM
> > > machines to install via desktop. We would need to alter the pages to
> > > tell people to use the alternate image (thank heavens that we do have a
> > > plan 'B'). However, if zram is unstable in kernel 3.11 it would have to
> > > be disabled. That a few testers have hit freezes is acceptable, but to
> > > release to eveyone... that's going to create a field day for the
> > > nay-sayers about how stable linux is.
> > >
> > > Just my thoughts on the matter.
> > >
> > > Regards,
> > >
> > > Phill.
> > >
> > >
> > > On 21 September 2013 19:58, Nio Wiklund <nio.wiklund@xxxxxxxxx
> > > <mailto:nio.wiklund@xxxxxxxxx>> wrote:
> > >
> > >     On 2013-09-21 20:27, Phill Whiteside wrote:
> > >     > I'm beginning the thought that
> > >     >
> > >
> > http://ubuntuforums.org/showthread.php?t=2162655&p=12735571#post12735571
> > >     > actually holds the key to this issue. They may well be 2 separate
> > >     bugs,
> > >     > but they both head towards zram. It seems very broken.
> > >     >
> > >
> > >     Yes, I think so too. Another bug or another condition that starts
> > that
> > >     race, that freezes the system.
> > >
> > >     I think zRAM makes Lubuntu perform better and I want it, but if we
> > >     cannot get rid of the freezing problem, we must consider having it
> > only
> > >     as an option in the live session (to make it possible to install with
> > >     low RAM), or skipping it completely and try zRAM again for the next
> > >     version, 14.04 LTS.
> > >
> > >     For example like this
> > >
> > >     In syslinux for the 32 bit system:
> > >
> > >     - 'Install Lubuntu' runs with zRAM
> > >     - 'Try Lubuntu without installing' runs without zRAM
> > >
> > >     And zRAM should not be used in the installed system.
> > >
> > >     -o-
> > >
> > >     I don't know about the 64-bit system. We need to consider syslinux,
> > >     grub-pc and grub-efi. I'm afraid it means a lot of cases to edit and
> > >     test.
> > >
> > >     Also, I think zRAM is not as important for modern computers with more
> > >     horsepower and RAM.
> > >
> > >     Best regards
> > >     Nio