Re: Question about xdp: how to figure out the throughput is limited by pcie

On Thu, Apr 13, 2023 at 01:59:44PM +0200, Jesper Dangaard Brouer wrote:
> Hi Andi and Acme,
> 
> Regarding below discussion and subj (top-posting as you don't need to
> read discussion to answer my perf questions).
> 
> Can we somehow use perf to profile things happening in PCIe ?
> E.g. Are there any PMU counters "uncore" events for PCIe ?
> 
>   Hint, we can list more PMU counter via Andi's ocperf tool[42].
>   # sudo ./ocperf list
> 
> Could we use the TopDown [toplev] model, to indicate/detect that the
> PCIe device (or PCIe root complex) is the bottleneck?

perf list uncore_iio_free_running has the bandwidth counters 
on Intel servers.

It can be tricky to identify the device for that, there was a patchkit
from Alexander Andronov to make it easier, but I'm not sure if it
made it in.

-Andi