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knezi

Member

Registered: 2014-04-13

Posts: 45

debugging slow performance

Hi,

I've got Latitude 5480. A couple of months ago, the laptop randomly started being really sluggish. Even vim lags a lot, compiling time is a lot longer, it takes a couple of seconds to switch windows...

I have tried to find the cause, but unsuccessfully. Everything seems to be normal. What I tried:

* `htop` - cpu load is almost zero; there are occasional peaks, but nothing unusual
* `free -m` - there's is enough free memory(6GB) and swap (8GB)
* `df -h`- free: 5 GB on root partition, 5 GB on home
* `hdparm` - 180 MB/s
* I'm running i3, tried mate without success
* try stoping all user processes - I got to about 10 - killed even pulseaudio, kept running only xorg & co.
* a clean new user
* often wifi keeps crashing (not sure if always) - I get No beacon heard and the time event is over already - restarting wpa_supplicant seems to resolve Wi-Fi, but not the lags
* dmesg - does not show any errors
* journalctl - nothing either
* HW test in BIOS - everything OK

Additional info:
Even when I boot up and fill in the passphrase to decrypt the LUKS partition, it visibly takes a lot longer than usual. So I guess it must be in the kernel or HW issue.
About four months before this started happening, I spilled beer on it. I got my keyboard changed, but the maintance guy said I could have problems with the motherboard. I'm not sure if it can be related as it was working for four months flawlessly.

For my setup - LVM on LUKS - hdparm was run on open encrypted partition

The worst thing, random reboot resolves this (sometimes two, three).

So, I know it's very random and hard to detect. If anyone can think of something I did not test, let me know.

jasonwryan

Anarchist

From: .nz

Registered: 2009-05-09

Posts: 30,424

Website

Re: debugging slow performance

Does it occur in the TTY, or just X? If just X, what is your graphics stack (version and logs)?

If not, what kernel? Have you tried -lts to see if you can reproduce?

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knezi

Member

Registered: 2014-04-13

Posts: 45

Re: debugging slow performance

Good point, I'll try TTY when  it happens next.
The problem it occurs randomly and now after three reboots it's resolved again.
I'm running the default kernel (5.1.5 currently) I'll try lts next time it happens.