[PATCH v3 1/3] testpmd: Do not enable mbuf fast release TX offload by default

[Morten Brørup]

> From: fengchengwen [mailto:fengchengwen at huawei.com]
> Sent: Tuesday, 5 August 2025 02.59
> 
> On 8/4/2025 3:42 AM, Morten Brørup wrote:
> > Enabling some offload by default may conflict with a manually
> configured
> > offload.
> > Specifically, the mbuf fast release TX offload, which conflicts with
> multi
> > segment packet TX offload, was enabled by default.
> > Therefore, mbuf fast release TX offload (the only TX offload which was
> > enabled by default) is not enabled by default anymore.
> 
> This may impact default performance, many vendor performance report has
> testpmd iofwd or macfwd case.

Yes.

IMO, any optimizations, mbuf-fast-free or mbuf-recycle, must be explicitly enabled, and documented in the performance reports when used.
Otherwise the performance reports give a false impression of higher performance, which is only available under certain circumstances.
I have complained about this before.
Which is also why mbuf-recycle must be explicitly enabled.
With this patch, the same finally applies to mbuf-fast-free too.
I could add a Fixes tag, but I think it is better to categorize this patch as an improvement rather than a bug fix.