Re: F33: preview swap-on-ZRAM using zram-generator feature change

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----- Original Message -----
> From: "Chris Murphy" <lists@xxxxxxxxxxxxxxxxx>
> To: "Discussion of Development and Customization of the Red Hat Linux Installer" <anaconda-devel-list@xxxxxxxxxx>
> Sent: Sunday, May 31, 2020 2:45:37 AM
> Subject: F33: preview swap-on-ZRAM using zram-generator feature change
> Hi,
> I'm following-up now that there's a preview of the change proposal ready:
> Highlights:
> - This is a system-wide change, for all editions and spins. And if
> Anaconda folks are still agreeable, it would be included on all
> install media where Anaconda is found: DVD/Live/netinstall.
> - Fedora Workstation edition will no longer create swap-on-disk by
> default. Instead swap-on-zram will be used. I expect to get buy-in
> from other editions/spins to do the same. This applies only to the
> default/automatic partitioning path, as previously discussed.
> - Tentative (proposed) defaults similar to what's used by IoT: ZRAM
> device is 50% RAM, with a 4GiB cap.
> The max size, which is configurable, is to help scale ZRAM device size
> for more uses cases and hopefully settle on a single default Fedora
> wide. This is a bit different than Anaconda's implementation, which
> doesn't activate above 2GiB, and uses a 1:1 ZRAM to RAM ratio. Based
> on my testing, even VM's with 3GiB RAM still prefer to use quite a
> decent amount of swap ~200MiB. If it's available. I think this
> adjustment is neutral to slightly better for Anaconda. And in any case
> the installer and installed environments will have the same
> configuration and implementation as a result of the change.
Back when ZRAM support was introduced in the installation environment the
aim was to enable installations and specially the more memory hungry graphical
installations on devices and VMs with less RAM. For devices with enough RAM
the installation could run just fine & ZRAM would be just extra overhead, so
we decided not to enable it here.

This was quite some time ago (6/7 years ago) and things certainly changed,
making the ZRAM overhead very likely totally negligible on current systems.

So I think dropping the conditions we have at the moment and simply always enabling ZRAM
with sensible configuration (like the IoT one mentioned above) should be fine.

> - Disable or somehow deprecate the Anaconda specific implementation,
> to avoid conflict and user confusion among the implementations.
IIRC we discussed using one of the scripts packaged in Fedora 
(I think it was provided by systemd ?), ideally the one used by the other
tools that are part of this system wide change. We just have not did that
just yet.

So I wonder if the image wide defaults change I guess it should be enough
if we coordinate dropping of our zram setup script at the same time the image 
wide change is done ?

> - Test day will be planned
> Critical feedback welcome.
> --
> Chris Murphy
> _______________________________________________
> Anaconda-devel-list mailing list
> Anaconda-devel-list@xxxxxxxxxx

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