pupswap behavior

[geo_c]

I'm posting here because I'm using fossapup, but it may be more a general pupswap question.

I ususally set up a pupswap file just in case some application gums up the ram, but on an old Dell Inspiron i5 laptop that I have with 3.65GB of usable ram, mounting the pupswap seems to cause the machine to use the swapfile when it doesn't appear to need to do so, which causes major lags in keyboard and mouse response.

I was doing a lot of file copying from midnight commander, and so I monitored the system using HTOP while trying to use other applications during the copy process. Basically HTOP reports very low CPU and RAM usuage, the RAM being somewhere around 1.5-2gb full at any point and a good 1-1.5gb still free. But the swapfile is swapping in 6-20mb at a time, causing the system to sporadically lag.

Unmounting the pupswap solves the issue. But it makes me wonder:

Is using a pupswap file really beneficial at all? Presumably it keeps the system from crashing in a pinch, but at what point does the system decide it needs to cache to the swap?

[williams2]

Is using a pupswap file really beneficial at all?

If using swap space causes the system to slow down a lot, so much that it unusable or almost unusable,
then no, using a pupswap file is not really beneficial at all?

It can be very usful in certain situations.
For example, downloading large files using the Mega plugin in Firefox seems to download the file completely to ram, then ask what name and where you want to save it.
Swapspace allows you to increase the effective space in ram Firefox can use, so you can download larger files than you could without swapspace.

I have run Puppy with a 256MB swapfile, and it would not use any space for days or weeks.
And then, for some reason, one day, it used about 100MB

You can set the swapiness kernel parameter. Search the internet for swappiness

The kernel has a OutOfMemory killer, but it does not work well.
See earlyOOM https://forum.puppylinux.com/viewtopic.php?t=2980
With EarlyOOM, Puppy has never slowed down or crashed because of a lack of ram.

I have been using this to run earlyoom:

killall -q earlyoom ; earlyoom -r0 -m1 --avoid 'Xorg' &> /tmp/yoom.log & disown

[geo_c]

You can set the swapiness kernel parameter. Search the internet for swappiness

Here's a detailed explanation of swapiness: https://www.howtogeek.com/449691/what-i ... change-it/

[LateAdopter]

Dimkr's Woof-CE builds have zramswap configured in rc.sysinit. It causes mouse lag and GPU hangs on my Intel box.
It's possible to remove it from a running system with:

Code: Select all

swapoff /dev/zram0
zramctl -r /dev/zram0

But it loads before Xorg so it could interfere with the initialisation of the display driver stack. I comment out the sections in rc.sysinit so that it doesn't get loaded.

[bigpup]

How to configure swappiness in puppy
https://oldforum.puppylinux.com/viewtopic.php?t=100219

[dimkr]

It causes mouse lag and GPU hangs on my Intel box.

How much RAM do you have? What GPU is it? Is it a Bluetooth mouse?

[LateAdopter]

It has 4GB RAM of which the integrated GPU in my extremely feeble Braswell N3150 takes 1.5GB

I normally use my Logitech K400+ proprietary wireless connection to its dongle. It's seen as a generic USB mouse and keyboard in the BIOS and until it's recognised as Logitech by linux. Then the I2C_HID and Logitech drivers get loaded. I have tried one of your builds with a PS/2 keyboard and USB mouse but it didn't change anything.

A previous problem with compression was related to the fact that it only has 256k L2 cache per core and no L3 cache.

I asked about zram swap on cagepup a3 and I wasn't expecting you to do anything about it. I just mentioned it here in case someone hits the same problem.

[bigpup]

Swap is set by default to start being used at 60% RAM still free or something close to that. (depends on Puppy version)

Use the info, in the topic I posted earlier a link to, set this to a lower point, to start using swap.

[dimkr]

A previous problem with compression was related to the fact that it only has 256k L2 cache per core and no L3 cache.

Can you share the output of for i in /sys/devices/system/cpu/cpu0/cache/index*/size; do echo "$i:`cat $i`"; done? I can disable zram on CPUs without L3 cache.

[bigpup]

May want to use this program.

Swapfile Manager
https://forum.puppylinux.com/viewtopic.php?t=6735

[LateAdopter]

A previous problem with compression was related to the fact that it only has 256k L2 cache per core and no L3 cache.

Can you share the output of for i in /sys/devices/system/cpu/cpu0/cache/index*/size; do echo "$i:`cat $i`"; done? I can disable zram on CPUs without L3 cache.

/sys/devices/system/cpu/cpu0/cache/index0/size:24K
/sys/devices/system/cpu/cpu0/cache/index1/size:32K
/sys/devices/system/cpu/cpu0/cache/index2/size:1024K