RE: [RFC PATCH 0/5] Introduce mempool object new debug capabilities

[Shani Peretz <shperetz@nvidia.com>]

> -----Original Message-----
> From: Morten Brørup <mb@smartsharesystems.com>
> Sent: Thursday, 19 June 2025 15:57
> To: Stephen Hemminger <stephen@networkplumber.org>; Shani Peretz
> <shperetz@nvidia.com>
> Cc: dev@dpdk.org
> Subject: RE: [RFC PATCH 0/5] Introduce mempool object new debug
> capabilities
> 
> External email: Use caution opening links or attachments
> 
> 
> > From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> > Sent: Monday, 16 June 2025 17.30
> >
> > On Mon, 16 Jun 2025 10:29:05 +0300
> > Shani Peretz <shperetz@nvidia.com> wrote:
> >
> > > This feature is designed to monitor the lifecycle of mempool objects
> > > as they move between the application and the PMD.
> > >
> > > It will allow us to track the operations and transitions of each
> > > mempool object throughout the system, helping in debugging and
> > > understanding objects
> > flow.
> > >
> > > The implementation include several key components:
> > > 1. Added a bitmap to mempool's header (rte_mempool_objhdr)
> > >    that represent the operations history.
> > > 2. Added functions that allow marking operations on an
> > >    mempool objects.
> > > 3. Dumps the history to a file or the console
> > >    (rte_mempool_objects_dump).
> > > 4. Added python script that can parse, analyze the data and
> > >    present it in an human readable format.
> > > 5. Added compilation flag to enable the feature.
> > >
> > > Shani Peretz (5):
> > >   mempool: record mempool objects operations history
> > >   drivers: add mempool history compilation flag
> > >   net/mlx5: mark an operation in mempool object's history
> > >   app/testpmd: add testpmd command to dump mempool history
> > >   usertool: add a script to parse mempool history dump
> > >
> >
> > Could this not already be done with tracing infrastructure?
> 
> I agree with Stephen on this.
> 
> And, if you plan to use this for performance measurements, you can use the
> coming PMU trace to trace the objects' movements between CPU caches and
> RAM, so you can discriminate between hot and cold objects.

We want to track when the transition of objects between the app and the PMD. So I don't know if PMU library is helpful in this case, isn't it?