[Winpcap-users] Better Performance

[Gianluca Varenni]

First of all, allocating some memory at every received packet is a bad idea. You should preallocate memory at the very beginning. 
Then, how many packets do you want to capture? What are you doing with all those packets in these arrays? 

Have a nice day
GV

  ----- Original Message ----- 
  From: Charu Agrawal 
  To: winpcap-users at winpcap.org 
  Sent: Tuesday, April 21, 2009 2:20 PM
  Subject: Re: [Winpcap-users] Better Performance


   

  Hi,

   

  This is what the code looks like - 

   

  This is all initialization code - 

   

                  if ((adhandle= pcap_open_live(d->name,            // name of the device

                                                                                                                   65536,                                  // portion of the packet to capture. 

                                                                                                                                                                                  // 65536 grants that the whole packet will be captured on all the MACs.

                                                                                                                   1,                                                           // promiscuous mode (nonzero means promiscuous)

                                                                                                                   1,                                           // read timeout

                                                                                                                   errbuf                                  // error buffer

                                                                                                                   )) == NULL)

                  {

                                  printf("\nUnable to open the adapter. %s is not supported by WinPcap\n", d->name);

                  

                                  return RETCODE_ERR;

                  }

   

                  //Set the filter string to the source ip address

                  //Only packets from this source address will be captured.

                  //This does slow down the capture a bit.

   

    NetMask=0xffffff;

    filter = "src 192.168.1.10";

   

                  

                  if(pcap_compile(adhandle, &fcode, filter, 1, NetMask) < 0)

                                  {

                                                  printf("\nError compiling filter: wrong syntax.\n");

   

                                                  pcap_close(adhandle);

                                                  return RETCODE_ERR;

                                  }

   

                  if(pcap_setfilter(adhandle, &fcode)<0)

                                  {

                                                  printf("\nError setting the filter\n");

   

                                                  pcap_close(adhandle);

                                                  return RETCODE_ERR;

                                  }                

                  

   

                  //Set the kernel buffer

                  

                  if (pcap_setbuff(adhandle,41943040) < 0)

                  {

                                  printf("\n unable to set buffer");

                  

                                  return RETCODE_ERR;

                  }

   

   

  Then I start the pcap_loop on a separate thread -  This function is called for each packet capture.

  I copy the data for all packets in a global array - image_buf 

   

  void packet_handler(u_char *dumpfileHandler, const struct pcap_pkthdr *header, const u_char *pkt_data)

  {

   

   //copy the packet data to image_buf and also store the packet length

   

                  

   image_buf[packetCounter] = (unsigned char*)(malloc(header->caplen*sizeof(unsigned char)));

   if(image_buf[packetCounter] ==  NULL)

   {             

                   printf("\n unable to allocate buffer");

                   return;

   }

   memcpy(image_buf[packetCounter],pkt_data,header->caplen);

   pkt_length[packetCounter]=header->caplen;

   

   packetCounter += 1; 

   

  }

   

  Please let me know if you need more details. I can zip and send the code file if needed.

   

  Thanks

  Charu

   

  From: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Gianluca Varenni
  Sent: Tuesday, April 21, 2009 1:51 PM
  To: winpcap-users at winpcap.org
  Subject: Re: [Winpcap-users] Better Performance

   

  Before trying to modify the WinPcap source code, I would try to understand what the bottlenecks are. What are you doing with the received packets?

   

  Can you show us the packet processing loop that you have in your code (even in form of pseudocode)?

   

  Have a nice day

  GV

    ----- Original Message ----- 

    From: Charu Agrawal 

    To: winpcap-users at winpcap.org 

    Sent: Monday, April 20, 2009 10:58 AM

    Subject: [Winpcap-users] Better Performance

     

    Hi,

     

    I am trying to figure out how to capture image frames most efficiently.  Each frame is approximately 20Mbytes.

     

    I am trying to achieve frame rate of 1-2 frames per second.  The packets are being received over a Gig eth dedicated link. ( Packets are sent over that link using only one source).

     

    I am unable to achieve this frame rate using winpcap. Would it be helpful to modify the Winpcap source code for better performance ? Has anyone here have any experience in modifying the winpcap source to achieve higher frame rate capture ?

     

     

    Thanks for your help in advance

    Regards

    Charu Agrawal


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