0

I see a 20% "System interrupt" CPU usage in the Windows 10 task manager if and only if a device is connected to the PC with serial port.

enter image description here

With the "LatencyMon" tool, I can see this comes from ACPI.sys.

I am in the situation described by:

High CPU usage by "System" and "System interrupts" (caused by ACPI.sys)

but more specifically this is linked to serial port: if I disconnect the device connected to the PC via serial port, the problem disappears.

Is there something to do:

  • on the motherboard ? (it is a KTQ87/Flex motherboard with Phoenix BIOS)
  • in Windows 10 device manager ?
  • I don't think there is something to do on the device connected by serial port itself, after all, serial communication is just high/low bits sent at a certain bitrate, there is no "configuration" except bitrate, number of stop-bits, etc.

?

Basj
  • 1,489
  • 7
  • 47
  • 90
  • 1
    “True” serial ports (as opposed to, say, USB adapters) use interrupts. Does your device send lots of data? – Daniel B Jul 04 '23 at 08:28
  • @DanielB Yes it sends hardware status a few times per second. So do you think that maybe it is normal and acceptable? – Basj Jul 04 '23 at 09:11
  • 1
    You may check, when the device is connected, what it looks like in Device Manager, and especially in Properties what driver it's using. – harrymc Jul 04 '23 at 17:23
  • Ok I'll report this @harrymc. – Basj Jul 04 '23 at 17:49

0 Answers0