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matt-3

Member

Registered: 2020-06-09

Posts: 23

IO more than 30-50 MB/s makes system unusably slow

Recently I've had issues with the system becoming unusably slow, seconds to respond to input and minutes to open apps. Using gnome system monitor I noticed that this seems to coincide with times when there is a lot of disk IO, like more than 30-50 MB/s. Does anyone have experience with this? Maybe I need to change the IO scheduler but I thought that was obsolete for SSDs. Besides, considering that it's an NVMe SSD, it should be able to handle much more than 30-50 MB/s.

Specs:
Framework 13
Intel i5-1240P
32 GB RAM
512 GB NVMe SSD

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“In science it often happens that scientists say, ‘You know that's a really good argument; my position is mistaken,’ and then they actually change their minds and you never hear that old view from them again… I cannot recall the last time something like that happened in politics or religion.” —Carl Sagan, 1987 CSICOP keynote address

seth

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Registered: 2012-09-03

Posts: 65,811

Re: IO more than 30-50 MB/s makes system unusably slow

Do you get IO errors in dmesg?
Is the system swapping out?
Is this gnome (wayland) specific?

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ugjka

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From: Latvia

Registered: 2014-04-01

Posts: 1,920

Website

Re: IO more than 30-50 MB/s makes system unusably slow

what is the make and model of the nvme ssd

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matt-3

Member

Registered: 2020-06-09

Posts: 23

Re: IO more than 30-50 MB/s makes system unusably slow

The SSD is Crucial P1 CT1000P1SSD8. It is 1 TB, I remembered incorrectly before.

There are no IO errors in dmesg.

Swap is not being used, indeed the RAM and CPU usage are generally both quite low when this occurs, because everything is waiting for disk IO.

I'm not sure if it's wayland-specific (I use sway not gnome btw). I guess next time it happens I will switch to a TTY and see if the commands there run faster.

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“In science it often happens that scientists say, ‘You know that's a really good argument; my position is mistaken,’ and then they actually change their minds and you never hear that old view from them again… I cannot recall the last time something like that happened in politics or religion.” —Carl Sagan, 1987 CSICOP keynote address

seth

Member

Registered: 2012-09-03

Posts: 65,811

Re: IO more than 30-50 MB/s makes system unusably slow

Thought because of "Using gnome system monitor" - what's the output of "mount", is /run/user/$UID a tmpfs? (The wayland socket is there by default - did you maybe redirect it onto some on-disk location?)
Running executables that are not in the file cache will expectably be (somewhat) slowed down, but this doesn't explain "seconds to respond to input" - what "input" exactly is this? Does it affect typing into a running terminal? (Not hitting enter since that'll likely write the history)

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ugjka

Member

From: Latvia

Registered: 2014-04-01

Posts: 1,920

Website

Re: IO more than 30-50 MB/s makes system unusably slow

I have the same exact SSD, and haven't observed anything like that with KDE. Can you run sudo iotop for any suspects?

Last edited by ugjka (2025-06-29 11:23:26)

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matt-3

Member

Registered: 2020-06-09

Posts: 23

Re: IO more than 30-50 MB/s makes system unusably slow

I don't think it's a problem with the SSD. My thought was the IO scheduler in the kernel. It seems like when one process reads/writes a lot, such as rustc building a large program, a long queue builds. I see that the IO goes to maximum and the system is almost unresponsive (maybe the scheduler has timeouts and eventually interrupts the big IO to allow these individual requests from other programs) until the queued IO is completed.

/run/user/1000 is a tmpfs. Interesting thought but I don't think it's the compositor, but rather the programs, which do disk IO for various reasons. I think the clock in waybar never stops ticking, for example, though I may be wrong.

It does affect a running terminal but I use fish so IO on input is to be expected. I could try the next time with sh, but it hasn't happened again yet.

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“In science it often happens that scientists say, ‘You know that's a really good argument; my position is mistaken,’ and then they actually change their minds and you never hear that old view from them again… I cannot recall the last time something like that happened in politics or religion.” —Carl Sagan, 1987 CSICOP keynote address

seth

Member

Registered: 2012-09-03

Posts: 65,811

Re: IO more than 30-50 MB/s makes system unusably slow

https://bbs.archlinux.org/viewtopic.php?id=306607
Do you get none of those IO errors?
How does it behave w/ the LTS kernel?

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matt-3

Member

Registered: 2020-06-09

Posts: 23

Re: IO more than 30-50 MB/s makes system unusably slow

No, there is no IO error whatsoever.

It did happen again though. Here is the Gnome System Monitor:

The part I circled in red shows this 30-50 MB/s region where the system is super slow. You can also see that not much RAM is used and the CPUs are all almost idle (waiting for IO?). I opened a terminal (very slow) and ran sh, which was then just as fast as normal, because it doesn't do disk IO, I guess.

I am not sure about LTS kernel but I have tried mainline and zen and both had the issue.

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“In science it often happens that scientists say, ‘You know that's a really good argument; my position is mistaken,’ and then they actually change their minds and you never hear that old view from them again… I cannot recall the last time something like that happened in politics or religion.” —Carl Sagan, 1987 CSICOP keynote address

Xephon

Member

Registered: 2024-12-22

Posts: 133

Re: IO more than 30-50 MB/s makes system unusably slow

Have you enabled TRIM?
What's the temperature of your SSD?

matt-3

Member

Registered: 2020-06-09

Posts: 23

Re: IO more than 30-50 MB/s makes system unusably slow

No TRIM because I am using LUKS.
My SSD is currently at 41°C. I will measure next time this happens.

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“In science it often happens that scientists say, ‘You know that's a really good argument; my position is mistaken,’ and then they actually change their minds and you never hear that old view from them again… I cannot recall the last time something like that happened in politics or religion.” —Carl Sagan, 1987 CSICOP keynote address

seth

Member

Registered: 2012-09-03

Posts: 65,811

Re: IO more than 30-50 MB/s makes system unusably slow

I am not sure about LTS kernel but I have tried mainline and zen and both had the issue.

Well… become sure about the LTS kernel…

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How to upload text · How to boot w/o GUI · Disable Windows Fast-Start! · Fix your xinitrc

matt-3

Member

Registered: 2020-06-09

Posts: 23

Re: IO more than 30-50 MB/s makes system unusably slow

I am not sure about LTS kernel but I have tried mainline and zen and both had the issue.

That's the next thing I would try, to see if it's due to a recent change.

OK, I will switch to LTS and see if it occurs.

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“In science it often happens that scientists say, ‘You know that's a really good argument; my position is mistaken,’ and then they actually change their minds and you never hear that old view from them again… I cannot recall the last time something like that happened in politics or religion.” —Carl Sagan, 1987 CSICOP keynote address