[Winpcap-users] About the packets loss , what is the bottleneck ?

Mon Sep 27 08:22:45 PDT 2010

A couple more ideas...

#1 Have you tried just looping pcap_next instead of relying on interrupts?
#2 Have you checked pcap_stats while running to see if receiver errors are occurring?

Can you show us your capture code?

Michael D. Black
Senior Scientist
Advanced Analytics Directorate
Northrop Grumman Information Systems

________________________________

From: winpcap-users-bounces at winpcap.org on behalf of yulou liu
Sent: Mon 9/27/2010 9:56 AM
To: winpcap-users at winpcap.org
Subject: Re: [Winpcap-users] EXTERNAL:Re: About the packets loss , what is the bottleneck ?

Yes, I have checked the sending of fpga in this way:  two fpga board ,
one for sending , another for receiving.  And made such experiment for
a great of times to ensure there is no problem on the fpga's side.

? 2010-9-27,20:31,"Black, Michael (IS)" <Michael.Black2 at ngc.com> ??:

> I believe your "route" is actually:
>
> FPGA -> ipqueue ->FPAGcard->ether->PCcard->ipqueue->winpcapbuf->winpcapuserbuf
>
>
> On your sending device are you checking to ensure the bytes sent match what you think you are sending?
>
> Many people assume that just because they made the function call means it worked.  Packet calls should always be checked to ensure the returned bytes match the sent bytes....otherwise you have to handle it properly.
>
> I suspect if anything is being dropped it's on the receiving end but you should double-check your sending anyways.
>
>
>
>
> Michael D. Black
> Senior Scientist
> Advanced Analytics Directorate
> Northrop Grumman Information Systems
>
>
> ________________________________
>
> From: winpcap-users-bounces at winpcap.org on behalf of liu.yulou at zte.com.cn
> Sent: Mon 9/27/2010 12:49 AM
> To: winpcap-users at winpcap.org
> Subject: EXTERNAL:Re: [Winpcap-users] About the packets loss , what is the bottleneck ?
>
>
>
> GV> Not at the moment with WinPcap. Having said that, I've used this double copy mechanism to bring several Gbps's to user mode without any packet loss (not with WinPcap, with custom hardware. However the buffering mechanism was the same).
>
> YL> 'double copy mechanism'  ,  Data copy from the user buffer to application(user mode) is the third copy ?
>
>
>
>
>
> GV>Are you dumping the packets to disk? If so, have you measured the dump-to-disk bandwidth?
>
> YL> Yes,   Dumping packets to disk is my final goal.  But right now ,  To avoid the limitation of the disk write speed ,  I just count the packets number in the receive  thread.   But  on the  rate of 614 Mbps,   sometimes  there are still packets loss.
>
> PS.     The route of packets transfer is :  FPGA BOARD sends data through ether net -->  PC'S  net card --> winpcap  kernel buffer --> winpcap user buffer  -->  receive thread count .   The FPGA's sending packets rate is about 614 Mbps ,   the size of  each packet is 1460 bytes,   every packet has a sequence number  ,   the sending process's  starting and stopping  can be controlled  .
>
> The app that  I make only counts the packet's number when a packet comes without saving .   While  the  last packet comes ,  the app will compare the number (it counts by itself)  with the sequence number (of the last packet).  Then I will know if there is packets loss.
>
>
>
>
>
>
>
> "Gianluca Varenni" <gianluca.varenni at cacetech.com>
> ???:  winpcap-users-bounces at winpcap.org
>
> 2010-09-21 07:41
> ??? ?
> winpcap-users at winpcap.org
>
>
> ???
> <winpcap-users at winpcap.org>
> ??
> ??
> Re: [Winpcap-users] About the packets loss ,        what is the bottleneck ? 
>
>              
>
>
>
>
>
>
> From: yulou liu <mailto:lyulou at gmail.com>
> Sent: Sunday, September 19, 2010 12:50 AM
> To: winpcap-users at winpcap.org <mailto:winpcap-users at winpcap.org>
> Subject: [Winpcap-users] About the packets loss , what is the bottleneck ?
>
>
> There is still the question about packets loss.
> Â Â
> According to the essayÂ  'Â Profiling and Optimization of Software-Based Network-Analysis Applications' ,Â Â Â  every packet is copied twice in the main memory before reaching the user.Â  In order to reduce the cost of CPU and the bus occupying of the SDRAM of pc,Â Â  is it possible to copy data directly from the kernel buffer to the final buffer ,Â  which I want the date keptÂ  in ?Â Â Â
>
> GV> Not at the moment with WinPcap. Having said that, I've used this double copy mechanism to bring several Gbps's to user mode without any packet loss (not with WinPcap, with custom hardware. However the buffering mechanism was the same).
>
> Â Â
> Here is another idea ---Â Â allocate several different user buffers , onceÂ aÂ user buffer is fulled , then let the next user buffer to save theÂ newÂ datas from kernel buffer.Â  Meanwhile copy datas from the first user buffer to disk (assume that the hard disk write rate is fast enough).Â  Is this idea work with the winpcap ?Â
>
> GV>Are you dumping the packets to disk? If so, have you measured the dump-to-disk bandwidth?
>
> GV
>
>
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