Below is the output from the cat,
/proc/net# cat ./emac_rfc2665_stats
ifSpeed                            : 100000000
dot3StatsDuplexStatus              : 3
ifAdminStatus                      : 1
ifOperStatus                       : 1
ifLastChange                       : 4294668617
ifInDiscards                       : 0
ifInErrors                         : 0
ifOutDiscards                      : 0
ifOutErrors                        : 1
ifInGoodFrames                     : 859480
ifInBroadcasts                     : 19952
ifInMulticasts                     : 0
ifInPauseFrames                    : 0
ifInCRCErrors                      : 0
ifInAlignCodeErrors                : 0
ifInOversizedFrames                : 0
ifInJabberFrames                   : 0
ifInUndersizedFrames               : 0
ifInFragments                      : 0
ifInFilteredFrames                 : 12
ifInQosFilteredFrames              : 0
ifInOctets                         : 1103907312
ifOutGoodFrames                    : 10122834
ifOutBroadcasts                    : 7

I can't find the TX underrun count, also from other emac_ files.
Yes, I am streaming using UDP.

Thanks,
Bin


On Mon, Mar 9, 2009 at 3:30 PM, Arie de Muijnck <[email protected]> wrote:

>  NFS is using a TCP connection which retries after errors. I suppose you
> use UDP to stream video data, and then you see the errors.
> If you do a "cat /proc/net/emac_rfc_*" you get a list of statistics
> counters. Look for the TX underrun count, it should stay zero. If not then
> the DMA burst size is the problem.
>
> Regards,
> Arie de Muijnck.
>
>
> ----- Original Message -----
> *From:* Bin Liu <[email protected]>
> *To:* Arie de Muijnck <[email protected]>
> *Sent:* Monday, March 09, 2009 16-11
> *Subject:* Re: reading compat flash causing emac network drop packets?
>
> Thank you for the reply, I will try that out and let you know the outcome.
> One question in my mind is if that is the case, why nfs reading can still
> go through.
>
> Bin
>
> On Fri, Mar 6, 2009 at 2:55 AM, Arie de Muijnck <[email protected]> wrote:
>
>>  From: Bin Liu
>>
>> Hi, I am trying to read transport stream file from compat flash and stream
>> out to the ethernet port,
>> and I am using customer DM6446 board, running 2.6.10 Linux.
>> When bitrate is low, less than 10 Mbps, there is no problem, but if
>> bitrate goes up to anything higher
>> than 15 Mbps, I am seeing the packet drops.
>> So far I have made sure there is no packet drop before packet is handed
>> over to ethernet emac driver,
>> and the cpu usage is not very high(around 30%) when dropping packet, if I
>> read the file from nfs server seem to be fine, so I doubt the cf driver is
>> causing the packet drop, anybody can shad some light
>>
>> This is I think a known 'feature'.
>> The maximum length of a DDRAM access burst is default set to 'infinite',
>> meaning a low-priority access may block a high-priority DMA transfer such as
>> used for the EMAC TX. See the errata sheet for the fix, the memory burst
>> control register is mentioned there, the default is the special value 0xFF
>> meaning infinite and should be set to 0x20 meaning 32.
>>
>> Regards,
>> Arie de Muijnck
>>
>
>
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