From: Stephen Hemminger <stephen@networkplumber.org>
To: Isaac Boukris <iboukris@gmail.com>
Cc: users@dpdk.org
Subject: Re: dumpcap: timestamp is years ahead when in pcapng format
Date: Tue, 19 Sep 2023 11:00:09 -0700 [thread overview]
Message-ID: <20230919110009.29e90615@hermes.local> (raw)
In-Reply-To: <CAC-fF8SM2F5LMGpkpBNpBsJXerSPi-BKnF=OU-ebcf1cjNUD7w@mail.gmail.com>
On Tue, 19 Sep 2023 19:35:55 +0300
Isaac Boukris <iboukris@gmail.com> wrote:
> Looking with git log, i found the original line was:
> return pcapng_time.ns + (delta * NSEC_PER_SEC) / rte_get_tsc_hz();
>
> Testing that does show a wrapping issue, e.g. (it stays around 08:05).
>
> 2023-09-19 08:05:24.372037 IP _gateway.domain > Rocky8.38358: 31975
> NXDomain 0/0/0 (46) 10
> 2023-09-19 08:05:21.577497 ARP, Request who-has _gateway tell Rocky8,
> length 46
> 2023-09-19 08:05:21.577599 ARP, Reply _gateway is-at 00:50:56:f8:92:76
> (oui Unknown), length 46 13
> 2023-09-19 08:05:22.833897 IP 192.168.202.1.50886 >
> 239.255.255.250.ssdp: UDP, length 174
>
> However with my change it looks fine and always increments. I dropped
> all the parenthesis:
> return pcapng_time.ns + delta / pcapng_time.tsc_hz * NSEC_PER_SEC;
The issue is that timestamping is in the fast path and that 64 bit divide is slow.
Looking at other alternatives.
next prev parent reply other threads:[~2023-09-19 18:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-19 14:40 Isaac Boukris
2023-09-19 16:35 ` Isaac Boukris
2023-09-19 18:00 ` Stephen Hemminger [this message]
2023-09-20 17:59 ` Isaac Boukris
2023-09-20 18:53 ` Isaac Boukris
2023-09-20 19:55 ` Isaac Boukris
2023-09-21 2:09 ` Stephen Hemminger
2023-09-21 5:14 ` Isaac Boukris
2023-09-21 15:31 ` Stephen Hemminger
2023-09-21 19:00 ` Isaac Boukris
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