From: Stephen Hemminger <stephen@networkplumber.org>
To: dev@dpdk.org
Cc: stable@dpdk.org, Reshma Pattan <reshma.pattan@intel.com>
Subject: Re: [PATCH 1/2] pcapng: revert use of reciprocal divide for timestamps
Date: Tue, 29 Sep 2026 08:36:08 -0700 [thread overview]
Message-ID: <20260929083608.1da61ca9@phoenix.local> (raw)
In-Reply-To: <20260927195015.78109-1-stephen@networkplumber.org>
On Sun, 27 Sep 2026 12:50:14 -0700
Stephen Hemminger <stephen@networkplumber.org> wrote:
> The use of recprocal divide caused in calculating timestamps
> caused overflow wraparound. This bug was introduced by confusion
> about bits, shift, and the test was too short to catch the
> problem.
>
> Go back to just doing the divide which ends up faster on many
> than having to do 128 bit math on many CPU types.
>
> This is not a pure git revert because there were other
> good things in that commit like handling earlier packets,
> and catching if TSC hz was zero.
>
> Fixes: 4fc65615b274 ("pcapng: improve performance of timestamping")
> Cc: stable@dpdk.org
>
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
Both applied to next-net
prev parent reply other threads:[~2026-09-29 15:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-27 19:50 [PATCH 1/2] pcapng: revert use of reciprocal divide for timestamps Stephen Hemminger
2026-09-27 19:50 ` [PATCH 2/2] test/pcapng: check timestamps over a long capture Stephen Hemminger
2026-09-29 15:36 ` Stephen Hemminger [this message]
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