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From: Stephen Hemminger <stephen@networkplumber.org>
To: Ben Magistro <koncept1@gmail.com>
Cc: dev@dpdk.org, ben.magistro@trinitycyber.com
Subject: Re: dumpcap w/ pcapng produces out of order/negative times
Date: Fri, 14 Jan 2022 08:15:47 -0800	[thread overview]
Message-ID: <20220114081547.2ebce3b2@hermes.local> (raw)
In-Reply-To: <CAKx8PBh-hr4KbQPbGnyyw-UGTDUX0pqa3D3T8-uK8=wBTi_NUg@mail.gmail.com>

On Thu, 13 Jan 2022 21:38:06 -0500
Ben Magistro <koncept1@gmail.com> wrote:

> While utilizing dumpcap with our app, we have observed the captured file
> producing out of order timestamps to include negative times.  We are still
> investigating the root cause but believe it is in lib/pcapng.  While doing
> some testing of this issue, this behavior was not observed with pcap.  In
> the attached pcap, there are 5 streams (same curl multiple times a few
> seconds apart), with streams 1 and 3 showing oddities.  Specifically,
> stream 1 is in the future relative to the packet order and stream 3 has a
> negative time.
> 
> Not sure if the pcap file will actual post/attach, if it doesn't will try
> something.
> 
> System: CentOS7 + devtoolset 9
> DPDK: v21.11

The library hast convert from TSC (cpu clock) to nanoseconds since 1/1/1970
The function pcapng_init computes the offset. 

  reply	other threads:[~2022-01-14 16:15 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-14  2:38 Ben Magistro
2022-01-14 16:15 ` Stephen Hemminger [this message]
2022-06-02 16:34   ` Ben Magistro

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