Zram on Slackware ARM

mralk3 · 03-15-2021, 09:22 AM

Has anyone found documention, blog posts, or white papers discussing zram on Slackware ARM? Specifically, using /tmp mounted in zram?

The only reliable information I found is here:
https://www.lotar.altervista.org/wik...m-in-slackware

What I am mostly interested in is how effective zram is on ARM... and if anyone uses it in production for meaningful workloads?

pan64 · 03-15-2021, 01:32 PM

for example: https://www.linuxquestions.org/quest...am-4175685851/
zram is not slackware specific.

mralk3 · 03-15-2021, 01:42 PM

Quote:

Originally Posted by pan64

for example: https://www.linuxquestions.org/quest...am-4175685851/
zram is not slackware specific.

I am aware that it is available on all Linux systems that have the zram kernel module compiled or built in to the kernel.

mralk3 · 03-15-2021, 02:21 PM

I wrote a Slackdoc to share what I could find. Hopefully, somemone else can use it as I am. I am very interested in information about how to use zarm as a file system to keep log files within it.

Zram in Slackware ARM and ARM64 Architectures

jloco · 04-18-2023, 04:14 AM

So, I randomly came across the guide linked here today google searching about zram.
Background: for a little while recently I had been running Debian (sid) on my PBP, as I wanted to see how the machine ran on another distro.

To my delight it ran pretty well, and a fresh out of the box install was much snappier than Slackware comes after install. Still, Debian isn't home and after a few weeks, running it had been enough for me. So back to Slackware with some new things to try. The different thing that stood out to me was Debian was using zram in place of a traditional swap partition. Now during the Slackware install I did setup a 4gb swap and enabled it, but now I want to try out some zram configs. All Debian was using was a 1gb zram, yet on the wiki page, it's setup to have 1gb zram per core. This equals 6gb of zram on the PBP, and is even higher than the included ram to begin with. I wonder if leaving this could hinder performance.

I'm interested to hear anyone else's experiences with zram, since this post has had 2 years to age, surely someone has this going by now. I'm going to try a few different things, and see how it fares. But outside of firefox, I haven't put anything resource intensive on here. I may install GNOME to see how that feels, since last time it was very sluggish on Slackware, but ran great on Debian. I've basically been using sway since it's so light on resources.

But I'd love to hear if anyone has any insight on zram on the PBP!

xp19375 · 04-27-2023, 07:06 PM

Quote:

Originally Posted by jloco

So, I randomly came across the guide linked here today google searching about zram.
...

I'm interested to hear anyone else's experiences with zram, since this post has had 2 years to age, surely someone has this going by now. I'm going to try a few different things, and see how it fares. But outside of firefox, I haven't put anything resource intensive on here. I may install GNOME to see how that feels, since last time it was very sluggish on Slackware, but ran great on Debian. I've basically been using sway since it's so light on resources.

But I'd love to hear if anyone has any insight on zram on the PBP!

I just tried this today on my PBP using mralk3's howto. The current kernel has the zram module compiled, so you don't need to recompile it. Everything seems to work fine so far, although I haven't tried anything stressing yet. The only complication for me is that the zram module doesn't load on boot automatically, so after boot I have to run

Code:

modprobe -v zram num_devices=6
swapon -a

I think it takes a little time for the /dev/zram? devices to get created so if you put this in rc.local, you might have to add a "sleep 1" after the first command.

mralk3 · 04-28-2023, 02:36 PM

Originally I was adding the zram block devices with a udev rule. I did it that way prior to MoZes adding in the /etc/rc.d/rc.platform.conf configuration file and the /etc/rc.d/rc.platform.d/ directory structure.

The way I do it now is by using rc.platform.conf to enable zram, configure the size, and how many block devices.

Zram support comes in the Aarch64 kernel already- no need to rebuild the kernel.

Here is an example of what I have on my pinebook pro and rockpro64 units at the end of rc.platform.conf

Code:

# Toggle ZRAM, set block device size and count
ZRAM_ENABLE=1
ZRAM_SIZE=2G
ZRAM_COUNT=1

Here is what I use on my pinebook pro and rockpro64 in /etc/rc.d/rc.platform.d/aarch64/zram.

Code:

####################################################################
# Script : /etc/rc.d/rc.platform/aarch64/zram
# Purpose: Perform boot time configuration activities for Hardware
#          Models using the rk3399 SoC.  This includes:
#          * RockPro64,
#          * Pinebook Pro
# Caller : This script is executed from /etc/rc.d/rc.platform
#          (which is loaded from /etc/rc.d/rc.M prior to rc.local) 
# Author : Brenton Earl <el0226@slackware.com> 
# Date...: 02-September-2022
####################################################################
# Note: This configuration file is managed by the Slackware packages
#       and is NOT user serviceable.  Any changes made here will be
#       removed when the 'a/sysvinit-scripts' package is upgraded.
#
#       To adjust the settings used for the actions applied here,
#       edit /etc/rc.d/rc.platform.conf and the settings will become
#       operative at the next boot.
####################################################################
#
# TODO Add Raspberry Pi and Honeycomb 

# Pinebook Pro and RockPro64 ZRAM settings:
case "$HWM" in
        "Pine64 Pinebook Pro"*|"Pine64 RockPro64"*)
        if [ "${ZRAM_ENABLE}" = "1" ]; then
                #ZRAM_SIZE=${ZRAM_SIZE:-1G}
                #ZRAM_COUNT=${ZRAM_COUNT:-4}

                echo "ZRAM:: Creating ${ZRAM_COUNT} block devices."
                modprobe zram num_devices=${ZRAM_COUNT} 

                echo "ZRAM:: Activating ${ZRAM_COUNT} swap devices at ${ZRAM_SIZE} each."
                for i in `seq 0 $(( ${ZRAM_COUNT[@]} - 1 ))` ; do
                        echo $ZRAM_SIZE > /sys/block/zram$i/disksize
                        mkswap /dev/zram$i > /dev/null 2>&1
                        swapon -p 50 /dev/zram$i
                done
        fi
        ;;
esac

It is pretty easy to add additional hardware models and drop these two files into /etc/rc.d after you do so. As an example, my raspberry pi 4 has 2 zram block devices and I use one as a swap file and another as a temporary file system (/tmp).

If you are building a lot of packages and have enough RAM to do so, I like to set up my build environment in RAM by using a zram block device as a temporary file system. Speeds things up a lot. Just be sure to edit your build scripts/configuration to save your packages to a more permanent storage after a build completes.

jloco · 04-28-2023, 02:53 PM

I had tampered with zram a bit. I changed what the wiki page recommends locally as well. I ended up setting up 2 - 2gb zram for swap and also a 1gb /tmp in zram. I'm hoping these will minimize writes to the emmc while building packages and such. So far I haven't run into any issues.

Someone elsewhere suggested doing the firefox cache in zram, and while it would be a decent idea for lowering writes, it seems I'd end up fetching the same data constantly, slowing down browsing overall. I haven't bothered messing with that yet though. Future task.

It did work seamlessly in my system after enabling in the rc.platform.conf file as well. As for changing all my slackbuilds, since I use many of them on other systems, I just mentally note I need to move packages out of /tmp before I reboot.

But as for zram overall... so far, so good. I need to set it up on x86 some day now