Hi Salvatore,I have enabled the verbose debugging mode on the command line and have appended the first 5000 lines of the dmesg output to this e-mail, running the current kernel from the Buster backports with the two kworker processes with high CPU load present.
After that, I have applied your patch to this kernel and rebooted with the patched kernel:
5.7.0-0.bpo.2-amd64 #1 SMP Debian 5.7.10-1~bpo10+1a~test (2020-08-28) x86_64 GNU/Linux
With your patch applied, the two kworker processes with high CPU load completely disappeared!
A snapshot of the "top" command shows the following top 10 processes: $ top top - 10:54:43 up 5 min, 3 users, load average: 0.18, 0.26, 0.13 Tasks: 225 total, 1 running, 224 sleeping, 0 stopped, 0 zombie%Cpu(s): 0.1 us, 0.1 sy, 0.0 ni, 99.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
MiB Mem : 15928.9 total, 14186.5 free, 900.8 used, 841.7 buff/cache MiB Swap: 0.0 total, 0.0 free, 0.0 used. 14711.4 avail MemPID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 344 root -51 0 0 0 0 S 0.3 0.0 0:00.10 irq/134-iwlwifi 425 root 20 0 0 0 0 I 0.3 0.0 0:00.09 kworker/5:3-events 1216 rtkit 21 1 152652 2856 2616 S 0.3 0.0 0:00.01 rtkit-daemon 1272 dirk 20 0 52376 17908 5460 S 0.3 0.1 0:00.02 hp-systray
1 root 20 0 169784 10436 7844 S 0.0 0.1 0:01.64 systemd2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu_gp4 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 rcu_par_gp 5 root 20 0 0 0 0 I 0.0 0.0 0:00.04 kworker/0:0-events_+ 6 root 0 -20 0 0 0 I 0.0 0.0 0:00.00 kworker/0:0H-kblockd
... Many thanks for looking after this issue and having found a fix for this! Best regards, Dirk Am 28.08.20 um 16:33 schrieb Salvatore Bonaccorso:
hi Dirk, On Wed, Aug 12, 2020 at 05:53:57PM +0200, Dirk Kostrewa wrote:Hi Salvatore, I just found out, that if none of the two USB ports is connected, there are two kworker processes with permanently high CPU load, if one USB port is connected and the other not, there is one such kworker process, and if both USB ports are connected, there is no kworker process with high CPU load. I think, this supports your suspicion that these kworker processes are connected with the overcurrent condition for both USB ports that I also see in the dmesg output. What puzzles me, is that I've observed these oddly behaving kworker processes also with the 5.6 kernel that I've tried from the Buster Backports repository.The kernel parameter variant did not work correctly as there are no dynamic debug output afaics (the double quotes seem to placed in the wrong place), please just try the setting at runtime instead: # echo 'file drivers/usb/* +p;' > /sys/kernel/debug/dynamic_debug/control What I was meaning is (and this is confirmed if you see the issue issue as well with the more recent kernels), that the specified commit actually uncovers the issue present possibly with the HW. Similarly to you someone else, where in known case with faulty HW, reported the following issue upstream: https://lore.kernel.org/lkml/20200720083956.GA4074@dhcp22.suse.cz/ I would like to see if we can collect as much information as possible and possibly crosscheck with upstream. If build the kernel with the attached patch (that is with the commit wich is supsected to uncover the issue), does then the issue goes away? You can folllow the quide in https://kernel-team.pages.debian.net/kernel-handbook/ch-common-tasks.html#s4.2.2 for the "simple patching and building" and quickly chekcing a patch. Regards, Salvatore
Attachment:
dmesg.txt.gz
Description: application/gzip