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<div class=Section1>
<p class=MsoNormal><span style='color:#1F497D'>Dear Mr. Varenni,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Thanks for your reply. I just
wanted to clarify a few points you have made. (Note: I am using a multicore
machine so the multithread is a natural choice and my processing code is
definitely not as optimized as your pcap code, but this is a solo project so I don’t
need to satisfy anyone else)<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo1'><![if !supportLists]><span
style='color:#1F497D'><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='color:#1F497D'>You mention, that I
should pre-allocate and reuse buffer space where to store packets and not
allocate new buffer. Do you mean something like: <o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:.5in'><span
style='color:#1F497D'>PCAPDATANODE myPacketBuffer[amountOfNeededPackets];
// store in a specific memory location predetermined <o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.5in;text-indent:.5in'><span
style='color:#1F497D'>Is PCAPDATANODE packetNode = new PCAPDATANODE(); not a
good way to go?<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l1 level1 lfo1'><![if !supportLists]><span
style='color:#1F497D'><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='color:#1F497D'>To prevent
overloading, I need to pause capture (not extraction) for a some amounts time
according to SYSTEM time settings, is there a command that can facilitate that?
Or should I simply stop the adapter, release it, and then reacquire when the
time comes to capture (also would this automatically flush the buffer)? At the
moment, I merely stopped the extraction but as you might have predicted the
capture continued and I simply continued processing where I last left it off.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Thanks again for you time,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span
style='color:#1F497D'><span style='mso-list:Ignore'>-<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span style='color:#1F497D'>Dennis<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Gianluca Varenni
[mailto:gianluca.varenni@cacetech.com] <br>
<b>Sent:</b> Monday, August 10, 2009 2:50 PM<br>
<b>To:</b> dennis.kg@gmail.com; winpcap-users@winpcap.org<br>
<b>Subject:</b> Re: [Winpcap-users] How to ensure all packets are captured<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman","serif"'>Moving
the processing code in a separate thread may or might not help. If you move the
processing on a different thread and use a FIFO/linked list to pass the packets
among the threads, you will need to copy the packets in your own allocated
buffer. Copying a packet is extremely fast, but it makes sense only if your
packet processing code is much more CPU intensive than copying the packet
itself. Also, using a different thread makes sense if you run on a multicore
machine, where basically you can use both the CPUs.</span><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman","serif"'>If
you go this way, remember to preallocate and reuse the buffers in which you
copy the packets, do not allocate a new buffer whenever you receive a
packet.</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman","serif"'>Hope
this helps</span><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Times New Roman","serif"'>GV</span><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
</div>
<blockquote style='border:none;border-left:solid black 1.5pt;padding:0in 0in 0in 4.0pt;
margin-left:3.75pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>-----
Original Message ----- <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal style='background:#E4E4E4'><b><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Arial","sans-serif"'> <a href="mailto:dennis.kg@gmail.com"
title="dennis.kg@gmail.com">Denis Kourktchan</a> <o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>To:</span></b><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'> <a
href="mailto:winpcap-users@winpcap.org" title="winpcap-users@winpcap.org">winpcap-users@winpcap.org</a>
<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Sent:</span></b><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'> Sunday, August 09,
2009 1:05 PM<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Subject:</span></b><span
style='font-size:10.0pt;font-family:"Arial","sans-serif"'> [Winpcap-users] How
to ensure all packets are captured<o:p></o:p></span></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'><o:p> </o:p></span></p>
</div>
<p class=MsoNormal>Hi Everybody,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I am writing an application that is intercepting packets
from a network and after reading a whole lot of posts regarding lost messages I
figured the fault is usually in application taking too long to process a batch
of packets which causes the overfilled buffer to replace oldest messages. So I
decided that the following setup is the best possible way to ensure that my
messages are not lost.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in'>1.<span style='font-size:
7.0pt;font-family:"Times New Roman","serif"'>
</span>Put capture (using pcap_next_ex()) into a different thread then the
processing.<o:p></o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in'>2.<span style='font-size:
7.0pt;font-family:"Times New Roman","serif"'>
</span>Store packets immediately upon extraction into a custom written linked
list, adding to the end and processing from the front (in different threads)
ensuring no mutex controls are necessary and no idle time.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Now here is the problem for which I need your expert advice,
since the pcap_next_ex() returns pointers to data, I still need to extract them
(I use for loop) before I can store which still preoccupies the capture thread
and slows down extraction process. So is there a better way to extract packets
without this delay?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I would appreciate any and all advice regarding the optimal
solution architecture wise.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Regards,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoListParagraph style='text-indent:-.25in'>-<span style='font-size:
7.0pt;font-family:"Times New Roman","serif"'>
</span>Dennis <o:p></o:p></p>
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<div class=MsoNormal align=center style='text-align:center'><span
style='font-size:12.0pt;font-family:"Times New Roman","serif"'>
<hr size=2 width="100%" align=center>
</span></div>
<p class=MsoNormal><span style='font-size:12.0pt;font-family:"Times New Roman","serif"'>_______________________________________________<br>
Winpcap-users mailing list<br>
Winpcap-users@winpcap.org<br>
https://www.winpcap.org/mailman/listinfo/winpcap-users<o:p></o:p></span></p>
</blockquote>
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