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From: Paolo Abeni <pabeni@redhat.com>
To: Jakob Unterwurzacher <jakob.unterwurzacher@theobroma-systems.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Dave Taht <dave.taht@gmail.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	"linux-can@vger.kernel.org" <linux-can@vger.kernel.org>,
	Martin Elshuber <martin.elshuber@theobroma-systems.com>
Subject: Re: [bug, bisected] pfifo_fast causes packet reordering
Date: Mon, 19 Mar 2018 13:32:30 +0100	[thread overview]
Message-ID: <1521462750.3059.12.camel@redhat.com> (raw)
In-Reply-To: <340a6c54-6031-5522-98f5-eafdd3a37a38@theobroma-systems.com>

Hi,

On Fri, 2018-03-16 at 11:26 +0100, Jakob Unterwurzacher wrote:
> On 15.03.18 23:30, John Fastabend wrote:
> > > I have reproduced it using two USB network cards connected to each other. The test tool sends UDP packets containing a counter and listens on the other interface, it is available at
> > > https://github.com/jakob-tsd/pfifo_stress/blob/master/pfifo_stress.py
> > > 
> > 
> > Great thanks, can you also run this with taskset to bind to
> > a single CPU,
> > 
> >   # taskset 0x1 ./pifof_stress.py
> > 
> > And let me know if you still see the OOO.
> 
> Interesting. Looks like it depends on which core it runs on. CPU0 is 
> clean, CPU1 is not.
> 
> Clean:	taskset --cpu-list 0 ./pfifo_stress.py
> 
> Broken:	taskset --cpu-list 1 ./pfifo_stress.py
> 
> Maybe related: CPU0 is where USB interrupts are handled:
> 
> > root@rk3399-q7:~# cat /proc/interrupts           
> >            CPU0       CPU1       CPU2       CPU3       CPU4       CPU5
> > 217:    2175353          0          0          0          0          0     GICv3 142 Level     xhci-hcd:usb5


Is not clear to me if you can reproduce the bug with the vanilla
kernel, or if  you need some out-of-tree nic driver. Can you please
clarify which NIC/driver are you using?

Thanks,

Paolo

  parent reply	other threads:[~2018-03-19 12:32 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-13 18:24 [bug, bisected] pfifo_fast causes packet reordering Jakob Unterwurzacher
2018-03-13 18:35 ` Dave Taht
2018-03-14  4:03   ` John Fastabend
2018-03-14 10:09     ` Jakob Unterwurzacher
2018-03-15 18:08     ` Jakob Unterwurzacher
2018-03-15 22:30       ` John Fastabend
2018-03-16 10:26         ` Jakob Unterwurzacher
2018-03-19  6:07           ` Alexander Stein
2018-03-19 12:32           ` Paolo Abeni [this message]
2018-03-19 12:56             ` Jakob Unterwurzacher
2018-03-21 10:01           ` Jakob Unterwurzacher
2018-03-21 18:43             ` John Fastabend
2018-03-21 19:44               ` Jakob Unterwurzacher
2018-03-21 20:52                 ` John Fastabend
2018-03-22 10:16                   ` Jakob Unterwurzacher
2018-03-24 14:26                     ` John Fastabend

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