Arch Linux

Trindol

Member

Registered: 2008-12-17

Posts: 37

nouveau and kslowd

When I use the nouveau driver, every 10-11 seconds a process called kslowd000 or kslowd001 uses 5% CPU. It alternates between 000 and 001. It doesn't happen with the proprietary NVIDIA driver, only nouveau. I've found references to this in my searches online, there's a link between kslowd and the drm module apparently, but most of these posts are from RC versions of 2.6.35. Killing a kslowd process does nothing, it comes back. Any ideas?

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: nouveau and kslowd

Just a wild guess https://bbs.archlinux.org/viewtopic.php?id=103346 but from a quick google search [1] seems unrelated. I think the upstream already knows about it. You can try downgrading to .34 and see if it's still an issue.

[1] http://www.gossamer-threads.com/lists/l … el/1238374 the last post, at the very bottom:

OK. From this hint I looked at the log between -rc1 and -rc2 and found
commit fbf81762e385d ("drm/kms: disable/enable poll around switcheroo
on/off").

Reverting this commit brings everything back to normal.

I think they're talking about Intel GPUs though.

http://osdir.com/ml/fedora-kernel-list/ … 00041.html for radeon and nouveau

Last edited by karol (2010-09-18 01:16:57)

Trindol

Member

Registered: 2008-12-17

Posts: 37

Re: nouveau and kslowd

It's something kernel related as I don't recall seeing this before and run nouveau from time to time. The sysload thing is not related. Only a brief 5% usage but still curious. Though I'm kind of surprised that there are no other reports of this really. Some of the 2.6.35 rc* posts on lkml are related but they are out of date by now.

nvidia 8300 gs for reference. nouveau has worked without a hitch in the past. It still does actually. Other reports of kslowd problems include screen flickering a 20% sysload which I don't see.

Last edited by Trindol (2010-09-18 01:20:31)

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: nouveau and kslowd

Many people are holding off because of the I/O congestion bug so if it's .35-specific, you might find yourself on the forefront of bug chasing :-)

Trindol

Member

Registered: 2008-12-17

Posts: 37

Re: nouveau and kslowd

Outside my ability unfortunately. Actually I never really saw the aforementioned io bug though I read about it. Of course my sysload is always 200-220% from BOINC.

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: nouveau and kslowd

I've found only this https://bbs.archlinux.org/viewtopic.php?id=103382

Trindol

Member

Registered: 2008-12-17

Posts: 37

Re: nouveau and kslowd

2.6.35.4-2 gives no joy.

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: nouveau and kslowd

2.6.35.4-2 gives no joy.

And downgrading to .34?

Trindol

Member

Registered: 2008-12-17

Posts: 37

Re: nouveau and kslowd

This bug is NOT present with 2.6.34.3-1.

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: nouveau and kslowd

This bug is NOT present with 2.6.34.3-1.

I'll check how is my fx 5500 + .35 kernel doing in the morning. If you think that's a new bug, report it upstream.

karol

Archivist

Registered: 2009-05-06

Posts: 25,440

Re: nouveau and kslowd

This bug is NOT present with 2.6.34.3-1.

I'll check how is my fx 5500 + .35 kernel doing in the morning. If you think that's a new bug, report it upstream.

I'm running 2.6.35.4-1 and I do see kslowd in powertop. Also, the sysload is a bit higher than it should be, but it's not much of an issue.
With 2.6.34.3-1 there are no problems.