[Winpcap-users] Better Performance

Thu Apr 23 17:59:29 PDT 2009

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 

	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 

		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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