[Winpcap-users] Packets capture latency

[Gianluca Varenni]

WinPcap is optimized for packet capture, at the expense of a jitter 
introduced from the time the packet is received by the driver to the time 
the packet is received by the user application. This means that the packet 
is received by the driver and timestamped, saved into a kernel buffer and 
later retrieved by the winpcap-based application. You can reduce this delay 
by playing with the timeout and mintocopy values (they are both accessible 
through the WinPcap API), obviously at the expense of the CPU load.

Have a nice day
GV



--------------------------------------------------
From: "Alimjan Kuramshin" <alimjankuramshin at gmail.com>
Sent: Wednesday, March 17, 2010 11:32 AM
To: <winpcap-users at winpcap.org>
Subject: Re: [Winpcap-users] Packets capture latency

> Hello, Gianluca!
>
> Thank you, for your attention and reply.
>
> Well, and within Wireshark too (but this is not quite correct place for 
> that).
>
> When i receive one packet from my device i'm emmideatly send back received 
> packet back(for testing)
> and using oscilloscope watch for my laptop ethernet card TX+ and TX- pins.
>
> Also, i've tried to use different handles(pcap_open) for capturing/sening 
> data, no changes the same result. :(
>
> 17.03.2010, в 20:06, Gianluca Varenni написал(а):
>
>> What is the original delay between the packets?
>>
>> Are you looking at the timestamps with wireshark?
>>
>> Have a nice day
>> GV
>>
>> --------------------------------------------------
>> From: "Alimjan Kuramshin" <alimjankuramshin at gmail.com>
>> Sent: Wednesday, March 17, 2010 9:58 AM
>> To: <winpcap-users at winpcap.org>
>> Subject: [Winpcap-users] Packets capture latency
>>
>>> Hello, everyone! My name is Alimjan and i'm developing custom board with
>>> the ethernet device and i've got some problem
>>> with capturing data from it ..
>>>
>>> I'm using Notebook Asus G1S with Windows XP + SP3 installed to connect 
>>> to
>>> my board. Using WinPcap(4.1.1), i'm capture data from the board. So, 
>>> i've
>>> found that delay between the captured packets is a very 'vary' i mean 
>>> that
>>> it has huge spread, e.g,
>>> at 10 mbits/s i've got 45-70 us delay, it is normal i gues, but some 
>>> times
>>> this delay grow up to 3-7 ms (milliseconds), for example, distance 
>>> between
>>> packets: 45 us, 46 us, 50 us, 47 us and so on.. then
>>> 4 ms, 7 ms, 1 ms, and then again 53 us, 47 us and so on, the repeat...
>>> Number of 'normal' delay is also very 'vary', delay may appear in a
>>> different numbers of received packets, no logic :(
>>>
>>> My laptop is directly connected to my board e.g. cross TX->RX, RX->TX, 
>>> no
>>> hubs or something. Also using oscilloscope connected to the  TX+ and TX-
>>> lines i've found that it is no delay between packet that my custom board
>>> (device) have send.  Anybody please, help me to solve this situation,
>>> may be i'm doing something wrong?
>>>
>>> P.S. i'm using winpcap exapmle code to capture the packets with callback
>>> method and within pcap_next_ex.
>>>
>>> P.P.S i'm sorry for my english spelling skill, i hope that you can
>>> understand my.
>>>
>>> Many thanks, bye..
>>>
>>> _______________________________________________
>>> Winpcap-users mailing list
>>> Winpcap-users at winpcap.org
>>> https://www.winpcap.org/mailman/listinfo/winpcap-users
>>
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