Re: Capture send packets in ZC mode

Alfredo Cardigliano <[email protected]> Thu, 26 Oct 2017 19:14:25 +0200
Newsgroups	gmane.linux.ntop.general
Message-ID	<[email protected]>
Hi
are you setting the flush flag to 1 when calling pfring_send()?

Alfredo

> On 26 Oct 2017, at 18:42, Charles-Antoine Mathieu <[email protected]> wrote:
> 
> Hi,
> 
> I'm trying to implement that, but my results looks odd. I'm trying to
> ping a bunch of ~20 hosts with a latency of ~1.77 ms every 5 seconds.
> 
> I capture time right after pfring_send and pfring_recv. For every batch
> I get around the same latency for every host but the latency range from
> 1ms to 300ms.
> 
> 37.187.9.32 : 11.532119ms
> 37.187.9.245 : 11.54512ms
> 37.187.9.124 : 11.525933ms
> ... 5 sec later the next batch ...
> 37.187.9.14 : 107.540483ms
> 37.187.9.17 : 107.519064ms
> 37.187.9.32 : 107.505375ms
> 
> I wonder if you are aware of some kind of buffering that might happen
> in the process to yield such results.
> 
> The ring is opened in ZC mode
> NIC model is Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network
> Connection (rev 01)
> 
> I'm using gopacket and ARISTA's nanotime package to capture a monotonic
> time which rely upon CLOCK_MONOTONIC, it seems more reliable and
> lightweight that time.Now() to me.
> https://github.com/aristanetworks/goarista/blob/master/monotime/nanotim
> e.go
> 
> On Fri, 2017-10-06 at 16:38 +0200, Alfredo Cardigliano wrote:
>> Hi
>> in ZC mode kernel is bypassed, thus you should send the packet and
>> call clock_gettime()
>> immediately after in order to compute latency (the same function is
>> used for RX in this case).
>> 
>> Alfredo
>> 
>>> 
>>> On 6 Oct 2017, at 16:34, Charles-Antoine Mathieu <charles-antoine.m
>>> [email protected]> wrote:
>>> 
>>> Hello,
>>> 
>>> I have a process that sends and receive ICMP packets using PF_RING.
>>> 
>>> I'd like to capture send and received packets to be able to compute
>>> the
>>> latency. When I'm not in ZC mode I get the send and the received
>>> packet
>>> in the capture. However in ZC mode I only get the received packets
>>> in
>>> the capture.
>>> 
>>> Is there a way go get the same behaviour in ZC mode ?
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