[Arm-dev] Using zram-swap

Gordan Bobic gordan at redsleeve.org
Fri Oct 12 16:03:31 UTC 2018

You do realize that some of us have been using swap-on-zram for the best
part of a decade, right?
It never required a systemd service, you just need an entry in
/etc/modprobe.d (optional), an entry in fastab (optionl) and a script in
/etc/sysconfig/modules (you can fold the other two I mentioned in here so
it's in a single place).
At the beginning zram only used LZO compression, and was single-threaded,
so we created one zram block device per CPU core, did mkswap on them and
did swapon with equap priority on all of those swap devices.
I had this on on Fedora and later RSEL6 on my SheevaPlug Toshiba AC100 as
far back as 2009, and I can't have been the only one.

In fact, this related ticket dates back to 2007, and I only got in on it in

Apparently that was a "can't fix" - worked for me since 2009 with the
solution I attached to that ticket.

On Fri, Oct 12, 2018 at 4:47 PM Robert Moskowitz <rgm at htt-consult.com>

> I have been working with Mark Verlinde, well actually he did the heavy
> lifting, to port zram to Centos...
> https://copr.fedorainfracloud.org/coprs/markvnl/zram-swap/
> A few of us are actively using it.
> Give it a try yourselves!
> As it is noarch, it should work on all Centos7 arch.
> On 10/7/18 1:06 PM, Robert Moskowitz wrote:
> >
> >
> > On 10/7/18 11:57 AM, Pablo Sebastián Greco wrote:
> >> Too many questions together... ;-)
> >>
> >> El 7/10/18 a las 08:58, Robert Moskowitz escribió:
> >>> I have very recently learned about zram-swap.  Fedora-29-arm is
> >>> using it.  It supposedly makes a considerable difference even over
> >>> HD swap.
> >> Do you have a link for me to read about that? I'd like to see some
> >> numbers on performance, specially on the CPU, because small ARM
> >> devices are not exactly fast to compress.
> >
> > You could ask on the Fedora-arm list where Peter Robinson (I believe
> > he is part of the Fedora development with heavy presence in the arm
> > work) recently explained, kind of, how F29-arm is using it.
> >
> >>>
> >>> Since many (potential) users of Centos-arm do not have a ready HD,
> >>> perhaps we can switch the image from a physical partition to zram?
> >>> Or at least instructions to change to this on the wiki.
> >> Switch might be difficult, but maybe generate a "tech preview"
> >> alternative build.
> >> This is the link to how we create the images, maybe  you could send
> >> me some changes to test
> >> https://github.com/CentOS/sig-core-AltArch/tree/master/image_build
> >
> > Minimally in the wiki, how to switch from a partition swap to zram. I
> > am working on learning more about it...
> >
> >
> > _______________________________________________
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> > Arm-dev at centos.org
> > https://lists.centos.org/mailman/listinfo/arm-dev
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