1

I am deeply wondering about this top (man page) output in uptime 5 hours 30 minutes only:

top - 00:41:41 up  5:48,  1 user,  load average: 0.36, 0.44, 0.63
Tasks: 281 total,   1 running, 280 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.2 us,  0.1 sy,  0.0 ni, 99.7 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
MiB Mem :  31827.3 total,  15894.9 free,   1933.8 used,  13998.6 buff/cache
MiB Swap:      0.0 total,      0.0 free,      0.0 used.  29321.2 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                                                                                                                                     
   4567 vlastim+  20   0 5229056 292040 141472 S   0.5   0.9   9:40.38 cinnamon                                                                                                                                    
    278 root     -51   0       0      0      0 S   0.2   0.0   7:29.32 irq/140-nvidia                                                                                                                              
    746 root     -51   0       0      0      0 S   0.0   0.0   5:52.90 irq/142-iwlwifi                                                                                                                             
   1423 root      20   0   25.1g 181056 118612 S   0.3   0.6   5:48.33 Xorg                                                                                                                                        
    280 root      20   0       0      0      0 S   0.0   0.0   2:23.89 nv_queue                                                                                                                                    
    276 root      20   0       0      0      0 S   0.0   0.0   0:31.17 nvidia-modeset/                                                                                                                             
  17208 root      20   0       0      0      0 I   0.0   0.0   0:15.22 kworker/2:1-events                                                                                                                          
    391 root      20   0       0      0      0 S   0.1   0.0   0:10.72 jbd2/nvme0n1p2-                                                                                                                             
  21613 vlastim+  20   0   32.7g 418536 216740 S   0.1   1.3   0:09.15 brave                                                                                                                                       

Laptop specs for question background

Using Linux Mint 21.1 Cinnamon with kernel 5.15.0-76-generic and Nvidia driver version 535.54.03.

I am playing one specific HTML5 game in Google Chrome (stable), I have some decent specs of my laptop, it's getting old though, I know:

  • CPU: Intel Core i7-7700HQ @ 2.80GHz base freq. / 3.80 GHz turbo freq.; (4 cores, 8 threads)

  • RAM: 32 GB DDR4 2400MHz, 2 sticks in dual-channel, disabled swap file

  • GPU: NVIDIA, GeForce GTX 1060, Max-Q Design, 6 GB GDDR5X VRAM

  • Display: Believe it or not, my laptop has a 15.6" UltraHD = 4K = 3840x2160 resolution, it was the cause for overheating of my laptop even if doing little tasks, so I have added a "normal" FullHD, and turned the built-in display off. No overheating now even when hours on the game.


The actual question

Sad to say that I do not understand how IRQ works / what they are for. So it is impossible for me to understand why my computer spends so much time dealing with it.

To clarify, from comment: Can they be avoided or limited to some extent? For example, I could switch to cable, which I do not have right now (standard Cat.6, I mean). Would that eliminate the hours of CPU time or would that cause just another IRQ to consume my CPU?


Clues

nvidia-smi

Mon Jul 17 01:41:49 2023       
+---------------------------------------------------------------------------------------+
| NVIDIA-SMI 535.54.03              Driver Version: 535.54.03    CUDA Version: 12.2     |
|-----------------------------------------+----------------------+----------------------+
| GPU  Name                 Persistence-M | Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp   Perf          Pwr:Usage/Cap |         Memory-Usage | GPU-Util  Compute M. |
|                                         |                      |               MIG M. |
|=========================================+======================+======================|
|   0  NVIDIA GeForce GTX 1060 ...    Off | 00000000:01:00.0  On |                  N/A |
| N/A   48C    P0              23W /  60W |    360MiB /  6144MiB |      0%      Default |
|                                         |                      |                  N/A |
+-----------------------------------------+----------------------+----------------------+
                                                                                         
+---------------------------------------------------------------------------------------+
| Processes:                                                                            |
|  GPU   GI   CI        PID   Type   Process name                            GPU Memory |
|        ID   ID                                                             Usage      |
|=======================================================================================|
|    0   N/A  N/A      1423      G   /usr/lib/xorg/Xorg                          132MiB |
|    0   N/A  N/A      4567      G   cinnamon                                     57MiB |
|    0   N/A  N/A     21650      G   ...ble-features=BlockInsecureDownloads      167MiB |
+---------------------------------------------------------------------------------------+

wavemon

┌─Interface───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│wlp60s0 (IEEE 802.11), phy 0, reg: n/a, SSID: =CENSORED                                                                                                                                                          │
├─Levels──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│                                                                                                                                                                                                                 │
│link quality: 73%  (51/70)                                                                                                                                                                                       │
│========================================================================================================================================================                                                         │
│                                                                                                                                                                                                                 │
│                                                                                                                                                                                                                 │
│signal level: -59 dBm (1.26 nW)                                                                                                                                                                                  │
│===============================================================================================                                                                                                                  │
│                                                                                                                                                                                                                 │
├─Statistics──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│RX: 9e+06 (3.26 GiB), drop: 10846 (0.1%)                                                                                                                                                                         │
│TX: 2e+07 (1.74 GiB), retries: 9k (0.0%)                                                                                                                                                                         │
├─Info────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│mode: Managed, connected to: =====CENSORED====, time: 6:51h, inactive: 6.0s                                                                                                                                      │
│freq: 5745 MHz, ctr1: 5755 MHz, channel: 149 (width: 40 MHz)                                                                                                                                                     │
│rx rate: 360.0 Mbit/s VHT-MCS 8 40MHz short GI VHT-NSS 2, tx rate: 400.0 Mbit/s VHT-MCS 9 40MHz short GI VHT-NSS 2                                                                                               │
│beacons: 238339, avg sig: -57 dBm, interval: 0.1s, DTIM: 2                                                                                                                                                       │
│power mgt: off,  tx-power: 22 dBm (158.49 mW)                                                                                                                                                                    │
│retry: short limit 7,  rts/cts: off,  frag: off                                                                                                                                                                  │
├─Network─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│wlp60s0 (UP RUNNING BROADCAST MULTICAST)                                                                                                                                                                         │
│mac: =====CENSORED====, qlen: 1000                                                                                                                                                                               │
│ip: ==CENSORED==/24                                                                                                                                                                                              │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
5
  • These are just time spent in IRQ processing for your GPU and wireless NIC, which is perfectly normal and expected. What is your concern?
    – Chris Down
    Jul 17, 2023 at 0:59
  • @ChrisDown Can they be avoided or limited to some extent? For example, I could switch to cable, which I do not have right now (standard Cat.6, I mean). Would that eliminate the hours of CPU time or would that cause just another IRQ to consume my CPU? Jul 17, 2023 at 1:09
  • Why would you want to avoid them? Interrupts are a totally normal part of network packet and graphics processing. What are you actually trying to do?
    – Chris Down
    Jul 17, 2023 at 10:25
  • @ChrisDown To save CPU time. Jul 17, 2023 at 13:18
  • Ok, save CPU time and do what instead? Resources are to be traded off, you don't usually just get CPU time for free.
    – Chris Down
    Jul 17, 2023 at 14:59

1 Answer 1

-1

I see nothing worrisome. Out of 5.5 hours of uptime your system has spent roughly 10 minutes serving interrupts.

Here's my situation on my desktop with a very fast AMD CPU (Ryzen 7 5800X):

uptime up 4 days,  6:32
24:50.41  [irq/118-nvidia]

The number could have been much higher but I don't use compositing.

On my laptop its Wi-Fi module is also quite prominent in terms of CPU time.

Nowadays a lot of UI operations are GPU accelerated (GTK uses OpenGL acceleration, your compositing WM also uses OpenGL or Vulkan acceleration), specially for web browsers, so that's totally expected.

2
  • In case you did answer original question before edit: To clarify, from comment: Can they be avoided or limited to some extent? For example, I could switch to cable, which I do not have right now (standard Cat.6, I mean). Would that eliminate the hours of CPU time or would that cause just another IRQ to consume my CPU? Jul 17, 2023 at 13:07
  • Do you feel like using Wi-Fi slows down your system? If not, you could simply ignore it. In Windows you'll get a single item System and that's it. In Linux you get deeper information. Maybe you could appreciate it ;-) Jul 17, 2023 at 13:42

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