Re: [BULK]Re: [BULK]Re: [PATCH] can: fix loss of frames due to wrong assumption in raw_rcv

[Stephane Grosjean <s.grosjean@peak-system.com>]

Hi Oliver,

${CUSTOMER}'s problem was rather a "loss of frame" issue than an 
"out-of-order" issue... In fact, it seems it was a simple "rookie" error 
of non-testing errno == ENOBUF after having written on the CAN socket.

Regards,

Stéphane

Le 04/07/2015 18:54, Oliver Hartkopp a écrit :
> Hi Stephane,
>
> On 29.06.2015 18:13, Oliver Hartkopp wrote:
>> Hi Stephane,
>>
>> On 25.06.2015 11:36, Oliver Hartkopp wrote:
>>>> Stephane Grosjean <s.grosjean@peak-system.com>
>>>> (..)
>>>> tells that he's facing some loss of frames with the PEAK-System 
>>>> PCAN-USB
>>>> adapter, in case of "relatively"  high bus load... He's running two
>>>> Kernels (3.19 and the last 4.1 patched with this recent "fix"). At the
>>>> moment, he says he always notes some frame leakage, especially when he
>>>> (for example) "resizes windows on his desktop"...
>
> Is $COSTUMERs problem fixed now?
>
> While testing the patches
>
> can: fix loss of CAN frames in raw_rcv
> http://git.kernel.org/cgit/linux/kernel/git/mkl/linux-can.git/commit/?h=testing&id=36c01245eb8046c16eee6431e7dbfbb302635fa8 
>
>
> and
>
> can: replace timestamp as unique skb attribute
> http://git.kernel.org/cgit/linux/kernel/git/mkl/linux-can.git/commit/?h=testing&id=a6ffebda241e513f6e839662d769b60b084d0957 
>
>
> I discovered an increase of out-of-order CAN frame receptions.
> My setup is a core i7 with a PCAN USB and a PCAN USB pro connected to 
> my full busload CAN source (1MBit/s, ~8008 frames/s).
>
> With 3.16 the out-of-order CAN frame reception is 'relatively' seldom.
> It's more with the PCAN USB and very few with PCAN USB pro.
>
> With the latest 4.2-merge the effect is reproducible after some time 
> (~10min).
>
> Examples:
>
>  drop detected: expected 204 received 212
>  drop detected: expected 237 received 204
>  drop detected: expected 212 received 237
>  drop detected: expected 68 received 69
>  drop detected: expected 70 received 68
>  drop detected: expected 69 received 70
>
> Obviously the frames do not get lost BUT are reordered.
>
> newcounter = frame.data[0];
> if (((counter + 1) & 0xFF) != newcounter) {
>  printf(" drop detected: expected %u received %u\n", counter + 1, 
> newcounter);
> }
> counter = newcounter;
>
> I'm a bit confused as this effect seems to increase with Linux kernel 
> version numbers. I removed all the changes for 4.1 in the 4.2-merge 
> kernel to have a 4.0 CAN subsystem (which was stable for a long time) 
> - but even this patch removal did not fix the out of order reception.
>
> Good thing: The latest changes in 4.1 (which patches) do not drop CAN 
> frames by accident.
>
> Bad thing: Why is the out-of-order reception increasing in Linux?
>
> I /assume/ some changes with RPS (receive packet steering) in the 
> network layer ...
>
>
> Regards,
> Oliver
> -- 
> To unsubscribe from this list: send the line "unsubscribe linux-can" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

--
PEAK-System Technik GmbH
Sitz der Gesellschaft Darmstadt
Handelsregister Darmstadt HRB 9183 
Geschaeftsfuehrung: Alexander Gach, Uwe Wilhelm
--