>30% CPU load increase with USB FLash plugged in (lots of SOF interrupts)

New Contributor

7 years ago

Dear Mr. @mrkozmic

Have you been able to fix this issue?

Like you, I'm currently testing a Cyclone V Board [1] with Linux Kernel 4.1.22 with RT Patch.

My USB Devices are a little different:

CV <--> USB3320 <--> SMSC_LAN9500

I don't have a hub connected to the USB-PHY. I am directly connecting an USB to Ethernet device.

I disabled the OTG, so that I only have two IRQs instead of the default 3 IRQs assigned by the dwc2 driver (USB driver).

I am currently watching around 20% CPU usage, but when I had the 3 interrupts, I also had 30% CPU usage exactly like you reported.

The number of interrupts observed on /proc/interrupts for IRQ45 (all USB interrupts) are also very very high too, around 7000 interrupts per second!

For debug, I also tested the non-RT version and this issue does not occur.

Best Regards,

Ventura

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