[Winpcap-users] Better Performance

[David Chang]

Charu,

malloc() is VERY expensive; especially for larger buffers. Are you 
saying that if you change the callback function to this...

void packet_handler(u_char *dumpfileHandler, const struct pcap_pkthdr 
*header, const u_char *pkt_data)
{
packetCounter++;
}

you still can't read 20,000 packets / sec? (I assume each packet is 
full, so this would be close to 30MB/sec)

What type of hardware (CPU, RAM, NIC, motherboard, etc) and O.S. do you use?

DC

Charu Agrawal wrote:
>
> Hi,
>
> Yeah. I understand that. But I doubt if that effects the speed much.
>
> I am doing some processing on the array later. But the processing is 
> not the bottleneck. It is the packet capture (packet_handler) that is 
> the bottleneck. Even if I remove
>
> All the code inside the packet_handler the packet capture still does 
> not meet expectations. We have nearly 20,000 packets. And as I 
> mentioned before we are looking to achieve a frame rate
>
> Of 30-60 Mbytes/s.
>
> Any ideas ?
>
> 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 3:33 PM
> *To:* winpcap-users at winpcap.org
> *Subject:* Re: [Winpcap-users] Better Performance
>
> 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 <mailto:cagrawal at altasens.com>
>
>     *To:* winpcap-users at winpcap.org <mailto: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 <mailto:cagrawal at altasens.com>
>
>         *To:* winpcap-users at winpcap.org
>         <mailto: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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