Hi Linus,

your patch works very good for me and others (please see https://forum.libreelec.tv/thread/4235-dvb-issue-since-le-switched-to-kernel-4-9-x/?postID=77006#post77006). No errors in recordings any more.
The patch was also tested on x86_64 (Revo 3700) with positive effect.
I agree with the forum poster, that there's still an issue when recording and watching livetv at same time. I also get audio dropouts and audio is out of sync.
According to user smp kernel 4.9.73 with your patch on rpi and according to user jahutchi kernel 4.11.12 on x86_64 have no such issues.
I don't know if this dropouts are related to this topic.

If of any help I could provide perf output on raspberry with libreelec and tvheadend.

Regards,
Josef 
 

Gesendet: Montag, 08. Januar 2018 um 23:16 Uhr
Von: "Jesper Dangaard Brouer" [off-list ref]
An: "Peter Zijlstra" [off-list ref]
Cc: "Josef Griebichler" <redacted>, "Mauro Carvalho Chehab" <redacted>, "Alan Stern" <stern@rowland.harvard.edu>, "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>, linux-usb@vger.kernel.org, "Eric Dumazet" <edumazet@google.com>, "Rik van Riel" <redacted>, "Paolo Abeni" <pabeni@redhat.com>, "Hannes Frederic Sowa" <redacted>, linux-kernel <redacted>, netdev <redacted>, "Jonathan Corbet" <corbet@lwn.net>, LMML <redacted>, "David Miller" <davem@davemloft.net>, torvalds@linux-foundation.org
Betreff: Re: dvb usb issues since kernel 4.9
On Mon, 8 Jan 2018 22:44:27 +0100
Peter Zijlstra [off-list ref] wrote:

On Mon, Jan 08, 2018 at 10:31:09PM +0100, Jesper Dangaard Brouer wrote:

quoted

I did expected the issue to get worse, when you load the Pi with
network traffic, as now the softirq time-budget have to be shared
between networking and USB/DVB. Thus, I guess you are running TCP and
USB/mpeg2ts on the same CPU (why when you have 4 CPUs?...)

Isn't networking also over USB on the Pi ?

Darn, that is true. Looking at the dmesg output in http://ix.io/DOg:

[ 0.405942] usbcore: registered new interface driver smsc95xx
[ 5.821104] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

I don't know enough about USB... is it possible to control which CPU
handles the individual USB ports, or on some other level (than ports)?
---
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer[http://www.linkedin.com/in/brouer]
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