Hello!
I recently installed Fedora 38 on a Beelink Mini S computer (AZW MINI S motherboard, Intel Celeron N5095 processor). Linux kernel 6.3.12.
Using ‘$ htop’ I found that at idle, one CPU core is under constant ~70% load:
It can be seen that the kernel is busy handling interrupts.
Further, with the help of ‘$ irqtop -d1’ it turned out that there are about 8000 interrupts per second at IRQ #16 when the computer is idle:
With the command ‘$ lspci -nnkv’ I saw the following regarding IRQ #16 on this computer:
"
00:04.0 Signal processing controller [1180]: Intel Corporation Dynamic Tuning service [8086:4e03]
DeviceName: Onboard - Other
Subsystem: Intel Corporation Device [8086:7270]
Flags: fast devsel, IRQ 16
Memory at 6001110000 (64-bit, non-prefetchable) [size=64K]
Capabilities:
Kernel modules: processor_thermal_device_pci_legacy
00:15.0 Serial bus controller [0c80]: Intel Corporation Serial IO I2C Host Controller [8086:4de8] (rev 01)
DeviceName: Onboard - Other
Subsystem: Intel Corporation Device [8086:7270]
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at 4010000000 (64-bit, non-prefetchable) [size=4K]
Capabilities:
Kernel driver in use: intel-lpss
00:1f.3 Audio device [0403]: Intel Corporation Jasper Lake HD Audio [8086:4dc8] (rev 01)
DeviceName: Onboard - Sound
Subsystem: Intel Corporation Device [8086:7270]
Flags: bus master, fast devsel, latency 32, IRQ 16
Memory at 6001120000 (64-bit, non-prefetchable) [size=16K]
Memory at 6001000000 (64-bit, non-prefetchable) [size=1M]
Capabilities:
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel, snd_sof_pci_intel_icl
00:1f.4 SMBus [0c05]: Intel Corporation Jasper Lake SMBus [8086:4da3] (rev 01)
DeviceName: Onboard - Other
Subsystem: Intel Corporation Device [8086:7270]
Flags: medium devsel, IRQ 16
Memory at 6001126000 (64-bit, non-prefetchable)
I/O ports at efa0
Kernel driver in use: i801_smbus
Kernel modules: i2c_i801
"
I also did a profiling of a running system and got the following:
It can be seen that most of the processor time is spent on the work of the azx_inerrupt, i2c_dw_isr, i801_isr and idma64_irq functions.
ChatGPT answered me:
"The azx_interrupt function is responsible for handling the interrupts of the sound card used in the system. It handles the processing of audio buffers and the transfer of audio data between hardware and software.
The i2c_dw_isr function belongs to the I2C bus driver and is responsible for handling interrupts associated with this bus. It provides interaction between devices connected to the I2C bus and the operating system.
The i801_isr function belongs to the SMBus bus controller driver and handles interrupts associated with this bus. It manages communication between devices connected to the SMBus and the operating system.
The idma64_irq function is responsible for handling interrupts associated with the DMA controller. It manages the transfer of data between devices and RAM, which reduces the load on the processor."
I don’t understand is this normal system behavior? Isn’t too much CPU time spent processing interrupts? I looked on another computer with Fedora 38 installed for this problem and there, it only executes interrupts related to the system timer. And on this computer (Mini S) there are more than 8000 interrupts per second associated with IRQ #16 when the computer is idle.
Is it normal?
Maybe some driver is missing?
Maybe some driver is not working properly?
Maybe the BIOS settings are wrong and something can be changed there?
Please tell me!
