lubuntu-qa team mailing list archive

[JM <meets@xxxxxx>]

Hello Nio,

On Fri, 11 Oct 2013 14:01:39 +0200
Nio Wiklund <nio.wiklund@xxxxxxxxx> wrote:

> > Hi,
> > 
> > I would have liked to read from your tests if the machine slows down by swapping too
> > early while some memory is still available or if it uses most of the physical RAM
> > before doing so. You could see it by having htop running in a console and keep on eye
> > on proc and ram use at the top of the console while starting and using applications.
> 
> I *was* watching the memory usage and process activity with htop :-)

Ok. :)


> It was swapping before the memory was fully used (Lubuntu is always
> doing that, with or without zRAM). I have not changed the swappiness
> from the default value.

I have found the same so far. During install time the install can even be slower and
slower while the use of the swap disk is increasing.


> > I have done tests with ZRAM, in an iso I am doing (a personal remix done with
> > ubuntu-builder) and have not finished yet. It consists in once having the
> > configuration default provided by the zram-config package, then in another ISO switch
> > to the configuration I have described before. 
> > 
> > I still have one test to do which could make a difference.
> > 
> > Linux kernels have been known to swap to disk too early since many years, and the
> > following configuration is a mean to limit the too early swappiness.
> 
> I think some (or many) people want it that way, to have a margin, when a
> large chunk of RAM is needed, and I have followed discussion threads
> about swappiness. Some people claim there should be different settings
> for servers compared to desktops & laptops (more swappiness for
> servers). I have not tested with different swappiness, so I have no own
> experience.

I have not studied/tested anything related to servers, I can't talk about that. I can say
with a Live desktop while installing the use of the swap disk increased up to almost 30%
of the available ram, while lots of ram was still available. 

(I'll show pics later when I will have found the time to perform the last tests).


> > So the test I want to do at last will consist in using the default zram-config
> > configuration and add just this: 
> > 
> > 
> > **********
> > vm.swappiness=0 
> > vm.vfs_cache_pressure=50 
> > 
> > # Uncomment the next line if we are running a laptop 
> > # vm.laptop_mode = 1
> > 
> > **********
> > 
> > as a file such as 50-local.conf in /etc/sysctl.d.
> > 
> > I wanted to try in Lubuntu but ubuntu-builder has not been able to redo a bootable ISO
> > from from the build directory after I added the file in the Lubuntu filesystem and
> > generated a new ISO.
> 
> I can try it in an installed system. It is easier and also more
> interesting for me :-P

Ok, I'll try to do what I suggested with a live USB and persistent mode because I would
like to see how the behavior is while using Ubiquity to install to hard drive.


> -o-
> 
> I think the ramdisk makes it harder for the memory management in the
> live system,

Sorry I didn't understand this part: did you mean "ramzswap" or did you mean "swap to
disk"/swap partition ? 

> which could explain why it choked earlier than the
> installed system with 256 MB RAM.

I think 256 MB RAM is too little for any modern system. Even the Ubuntu Openbox Remix I
work on, which has a few components less does not behave in a very snappy way on a
machine with so little RAM, and let's not forget what the GPU can bring or remove, when
it works with shared memory.
 
Regards,
Mélodie