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shermand100 / PiNodeXMR

Monero Node for Single Board Computers with Web Interface and additional tools pre-configured. Self Installing.
GNU General Public License v3.0
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ZRAM/ZRAM-swap optimizations #16

Open ChiefGyk3D opened 3 years ago

ChiefGyk3D commented 3 years ago

While Swap is great for not having enough RAM, it should be discouraged. On my Odroid HC2 was found to be set at 100 as shown by cat /proc/sys/vm/swappiness I recommend lowering to 5 or 10 to discourage swapping but not disable it. Lower is better sudo sh -c 'echo "" >> /etc/sysctl.conf' sudo sh -c 'echo "#Set Swappiness lower" >> /etc/sysctl.conf' sudo sh -c 'echo "vm.swappiness = 10" >> /etc/sysctl.conf' I notice you are also using ZRAM which was another recommendation, may be wise to maybe see this documentation to set it up for Pi, looks to apply for Odroid/armbian as well for me.

ChiefGyk3D commented 3 years ago

I'm reading this documentation here on ZRAM, this may actually improve it, so I may have been wrong on the swappiness because of how ZRAM works but we can make some additional tweaks I will test out https://haydenjames.io/raspberry-pi-performance-add-zram-kernel-parameters/

ChiefGyk3D commented 3 years ago

It appears we can possibly use a script from this project to increase performance for our devices by utilizing zram more for swapping and compress it up to 3X and making swapping more efficient so our systems are more stable overall. https://github.com/foundObjects/zram-swap

then adding four paramaters to the /etc/sysctl.conf vm.vfs_cache_pressure=500 vm.swappiness=100 vm.dirty_background_ratio=1 vm.dirty_ratio=50

shermand100 commented 3 years ago

The commit above was to the Armbian branch.

Doing a build on Pi4 at the moment and will check the behaviour of the systemctl commands behaves the same. I'm almost certain it will be. So then swappiness of 10% will be project wide.

As for ZRAM it's something I'd need to research more of to be able to implement myself. If you knock something together that survives the Monero build and optimises daily use then I'm all for testing and implementation.

I'm no expert in this field but my first impression is that it takes some RAM and segregates it off as compressible ZRAM. I'd want to double check the behaviour of a Monero build which is very RAM heavy normally. Would that fill and then bleed from ZRAM into RAM then maybe into swap? I can't imagine how it's page management is handled on a large compilation.

ChiefGyk3D commented 3 years ago

As for ZRAM it's something I'd need to research more of to be able to implement myself. If you knock something together that survives the Monero build and optimises daily use then I'm all for testing and implementation.

I'm no expert in this field but my first impression is that it takes some RAM and segregates it off as compressible ZRAM. I'd want to double check the behaviour of a Monero build which is very RAM heavy normally. Would that fill and then bleed from ZRAM into RAM then maybe into swap? I can't imagine how it's page management is handled on a large compilation.

Agreed on the testing part. I am having it build a brand new install on my second HC2 as we speak and will pipe in the ZRAM tweaks and then immediately test a new Monero build, then incorporate my Symlink setup of the HDD, and then test the manual block loading as well and compare results on system load. During a manual load I am noticing SIGNIFICANT lag when running things, the web server is sluggish as is even htop via SSH and that's with 8 CPU cores on a Samsung Exynos 5422 and 2GB of DDR3 on it. So even the Pi4 would take a little performance hit for the improvements I propose. But I feel it would add a serious advantage without pushing for 4GB Pi 4's so much.

Granted I personally plan everything to move to 4GB Pi 4's with 512GB SSD or larger over USB 3.0 because I want to get this all working with PoE for all my private nodes. I'm still going to continue on the armbian side regardless due to more powerful hardware available.

shermand100 commented 3 years ago

Commit to change swappiness of Raspberry Pi systems to 10 (from 60) https://github.com/monero-ecosystem/PiNode-XMR/commit/e883bbb948b698bf387ad94f8e188557d5a02714

ChiefGyk3D commented 3 years ago

I tested this on an Odroid HC2 and built Monero in 3 hours with the system being FAR MORE responsive and reactive to other commands whilst in operation I.e. webui and htop. I highly recommend testing this on the Pi platforms as well

shermand100 commented 3 years ago

Ok so the swappiness is to hardware globally as 10. I imagine other Odroid specific optimisations will be found. Because of this I'm reluctant to force them to all users with other hardware. How about a new system settings menu from the web terminal where a user selects their hardware from a list which runs a script making optimisations like this? Are these sorts of changes big enough to perhaps make this selection of hardware before install?