From: Alan Stern <stern@rowland.harvard.edu>
To: Michal Hocko <mhocko@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Greg KH <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: kworker/0:3+pm hogging CPU
Date: Mon, 20 Jul 2020 13:38:07 -0400 [thread overview]
Message-ID: <20200720173807.GJ1228057@rowland.harvard.edu> (raw)
In-Reply-To: <20200720163355.GA4061@dhcp22.suse.cz>
On Mon, Jul 20, 2020 at 06:33:55PM +0200, Michal Hocko wrote:
> On Mon 20-07-20 11:12:55, Alan Stern wrote:
> [...]
> > sudo echo 'module usbcore =p' >/debug/dynamic_debug/control
> >
> > Then wait long enough for some interesting messages to appear in the
> > kernel log (it should only take a few seconds if the worker thread is as
> > busy as you say) and collect the output from the dmesg command.
> >
> > To turn dynamic debugging back off when you're finished, use the same
> > command with "=p" changed to "-p".
>
> [ 95.395815] hub 2-0:1.0: state 7 ports 6 chg 0006 evt 0000
> [ 95.395824] usb usb2-port1: status 0088, change 0000, 5.0 Gb/s
> [ 95.395838] usb usb2-port2: status 0088, change 0000, 5.0 Gb/s
> [ 95.396016] hub 2-0:1.0: hub_suspend
> [ 95.396023] usb usb2: bus auto-suspend, wakeup 1
> [ 95.396029] usb usb2: bus suspend fail, err -16
Okay, that's the problem. You may get more specific information about
the suspend failure if you turn on dynamic debugging for the xhci-hcd
module (same command as above but with xhci-hcd instead of usbcore).
If you want a quick way to prevent this from happening, you can do:
sudo echo on >/sys/bus/usb/devices/usb2/power/control
That won't actually fix anything, but it will stop the system from
automatically trying to suspend usb2 root hub.
Alan Stern
next prev parent reply other threads:[~2020-07-20 17:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 8:39 kworker/0:3+pm hogging CPU Michal Hocko
2020-07-20 13:58 ` Alan Stern
2020-07-20 14:32 ` Michal Hocko
2020-07-20 15:12 ` Alan Stern
2020-07-20 16:33 ` Michal Hocko
2020-07-20 17:38 ` Alan Stern [this message]
2020-07-20 17:45 ` Michal Hocko
2020-07-20 17:48 ` Alan Stern
2020-07-20 18:16 ` Michal Hocko
2020-07-20 20:02 ` Alan Stern
2020-07-21 5:59 ` Michal Hocko
2020-07-21 14:33 ` Alan Stern
2020-07-21 16:00 ` Michal Hocko
2020-07-21 16:14 ` Alan Stern
2020-08-29 9:50 ` Salvatore Bonaccorso
2020-08-29 15:59 ` Alan Stern
2020-08-31 11:37 ` Mathias Nyman
2020-09-01 15:27 ` Michal Hocko
2020-09-04 15:57 ` Dirk Kostrewa
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