On Sunday, June 7, 2020 11:51:38 AM MST Konstantin Kharlamov wrote:
> Hello! I see a proposal to enable zram by deafult¹. If I correctly
> understand this is the thread where it's being discussed. I have a few
> questions, answers to which probably would be nice to add to the
> proposal.
>
> 1. It says ZRAM gets enabled on upgrade. What's gonna happen to systems
> with ZSWAP is enabled? I guess it doesn't make sense to keep them both.
> 2. I was a bit shocked to see comparison to a system with 16GB of RAM.
> I admit the more the better, but most people still have only 8GB on
> their laptops/PCs, and sometimes there's just 4GB of RAM.
> My question is: given people with 4GB of RAM, are you sure that
> handing 2GB over to ZRAM gonna improve their experience?
>
> The third question touches the paragraph "Why not zswap?". The only
> point it mentions is that swap-device is not encrypted. Fair enough,
> although I wonder why this never has been regarded as a problem before.
An important consideration is that zram is *also* not encrypted. If that's
enough to rule out zswap, it should be enough to rule out zram too.
> I have an actual user experience which suggests ZSWAP might be a better
> choice. My gf is using Macbook with Fedora, with 4GB of RAM and an SSD
> device. She loves opening lots of tabs in a browser, and as you can
> expect RAM gets quickly exhausted.
>
> With 2GB of SSD SWAP she was getting lags sometimes ("sometimes", SWAP
> on SSD is much faster than on HDD). 3-4 months ago I enabled 1GB of
> ZSWAP, and lags are gone.
>
> Would your proposal with ZRAM help here? Sadly no, there's more to the
> story. The 2GB of SWAP turns out not to be enough, it gets regularly
> exhausted. I even had to create a script that pops up a warning when
> SWAP is low on space, so she'd close some tabs² (for some boring reason
> it's a bit hard to increase SWAP space there).
>
> Let me emphasize that: 3GB of compressed RAM (ZSWAP + SWAP) is not
> enough! The moral of this story is that you can't get away with only
> ZRAM without any disk SWAP. You need disk SWAP. And if you have disk
> SWAP, ZSWAP fits more nicely there as a compressing buffer before the
> data finally spills over to disk.
>
> 1: https://fedoraproject.org/wiki/Changes/SwapOnZRAM#Why_not_zswap.3F
> 2:
> https://github.com/Hi-Angel/scripts/blob/master/warn-on-low-memory.pl
Zswap sounds like an excellent idea to look into instead of zram. Not only
that, but it'd allow traditional entry in fstab to configure it, instead of
some systemd magic that nobody knows about.
--
John M. Harris, Jr.
_______________________________________________
devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx
To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx
Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/
List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
