zRAM

[Ali Linx (amjjawad)]

Hi Leszek,

I must say that I'm so much happy, glad and comfortable reading your pure
technical words in your Email. You made my day, thank you so much. Such
'quality' is very much needed on the mailing list and I wish we could
follow your steps. THANK YOU!
No wonder, if you are a developer, you must be wise and choose your words
carefully and your explanation is amazing. Anyone and everyone can
understand it.


On Sun, Jun 9, 2013 at 12:44 PM, Leszek Lesner <leszek.lesner at web.de> wrote:


> It will raise the SWAP size. This in particular will not help much(if you
> already have 1 GB).


Glad we are on the same page :)
As long as SWAP is 1GB for example, zRAM is not going to help much.


> But for SWAP files/partitions you can set priorities. So
> that for swap it should use zram first and then the hdd or ssd in your
> computer.
>

+1
 Definitely. Otherwise, zRAM will be a total waste and helpless.


And one rule that applies always RAM is faster than hdd/ssd.


+1
Preciously!



> So swapping out
> to a compressed ramdrive might be a little bit slower than directly
> writing to
> your memory (this depends on the cpu and the number of cpus) but it is
> definitely faster then writing to your harddrive.
>

+1



> On much workload which uses lots and lots of memory (usually the
> webbrowser is
> a memory hungry beast no matter if chromium or firefox or xyz) this could
> dramatically help the performance.


It helped me at the beginning but then, it did not. I was using Chromium
during that test, if I remember correctly and I guess I still have the
report and screenshot.

http://amjjawad.blogspot.com/2013/05/facebook-on-lubuntu-1210.html<http://amjjawad.blogspot.ae/2013/05/facebook-on-lubuntu-1210.html>



> (especially also when you think about live
> usb sticks with persistency files/partitions + swap file/partiton on it - I
> admit this might be a rare case but I have seen this before more than once
> already)


I am not sure I got that but never mind.



> When I first starting using Ubuntu and Lubuntu, when I first joined the
> > Ubuntu Forms, the GURUs and the Expert people over there taught me
> > something.
> > If you have 1GB-2GB RAM or more, SWAP Partition = RAM
> > If you have LESS than 1GB RAM, SWAP Partition = 2 * RAM
>
> It depends.
>

Of course, depends on what you use and need and on your machine as well.



> Chromium for example sometimes needs lots and lots of ram and in this case
> it
> might be wise to also have more SWAP space for this.
> As /tmp nowadays also tends to be written to ram it might be also helpful
> to
> have a bigger swap file/partition depending on how you work and what
> applications you use.
> Audacity (the audio editor) for example writes everything to /tmp if you
> don't
> save your project somewhere. This can fill the /tmp directory very fast if
> you
> are cutting an interview or a large music file.


Chromium is a RAM beast, no doubt about it.

For my machines, I have two machines with 512MB RAM. SWAP is always 1GB RAM.

I have two Core i5 with 4GB RAM and my SWAP is 4GB as well.



> > Whenever I use my test machines with 512MB RAM, I always set SWAP
> Partition
> > to be 1GB RAM. NO MATTER how much my HDD Size is.
> > Having that said, I do have NO problems at all whether installing from a
> > LiveCD or LiveUSB.
>
> Not everyone who wants to install Lubuntu has a swap space on disk for it
> on
> first installs.


If this is the one and only Linux System to be installed then YES!
If the HDD is empty and this is the first install (example: wiped HDD) then
also YES!


It might be very convenient then to double the memory available
> just by enabling zram (which uses the same amount as RAM is available as
> virtual swap space compressed in RAM).


I am so sorry, my friend but I must disagree with this. At least, my tests
shows that zRAM did not double the RAM size. I had 1GB SWAP and when zRAM
was enabled, it became 1.2GB and to make sure, I disabled my SWAP and still
the same result:
http://3.bp.blogspot.com/-pT51RQGkvVc/UYbdyOIyjRI/AAAAAAAAAcg/4MOnLLT8GkE/s1600/2013-05-05-174643_1280x1024_scrot.png



> At least it is more convenient than
> telling those people to firstly create a swap partition with gparted and
> either
> enable it with the terminal or reboot the live system to be able to install
> the system on the pc.
>

+1



> I hope that explains some things .
>

It explains a lot of things, many thanks :D



> Ah and btw. we here at ZevenOS also tested zram in Neptune (yeah I am the
> main
> dev of Neptune & ZevenOS) for about half a year and it worked fine so far
> and
> we made particullary good experiences with live systems + persistency
> (which
> is one of Neptunes primary goals).


Can I join your team? :P


Anyway, I'm glad that Julien agreed to add it by default so I can't wait
for some HEAVY tests :D


-- 
*Best Regards,*
*amjjawad <https://wiki.ubuntu.com/amjjawad/>*
*Start Ubuntu<https://wiki.ubuntu.com/Lubuntu/CommunicationsTeam/WOWLubuntu/StartUbuntu>
*

*Test Machine: ASUS F3F Laptop - **Intel Core Duo T2350 @ 1.86GHz with
489MB RAM*
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