Re: [PATCH v16 0/4] add support for self monitoring

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 18 Nov 2024 08:37:02 +0100
Tomasz Duszynski <tduszynski@marvell.com> wrote:

> This series adds self monitoring support i.e allows to configure and
> read performance measurement unit (PMU) counters in runtime without
> using perf utility. This has certain advantages when application runs on
> isolated cores running dedicated tasks.
> 
> Events can be read directly using rte_pmu_read() or using dedicated
> tracepoint rte_eal_trace_pmu_read(). The latter will cause events to be
> stored inside CTF file.
> 
> By design, all enabled events are grouped together and the same group
> is attached to lcores that use self monitoring funtionality.
> 
> Events are enabled by names, which need to be read from standard
> location under sysfs i.e
> 
> /sys/bus/event_source/devices/PMU/events
> 
> where PMU is a core pmu i.e one measuring cpu events. As of today
> raw events are not supported.

It would be good to have a working useful example of what and how
these could be used.

Given that most DPDK applications are poll mode, it is not clear
how these could be useful.

There is a lot of work that perf does to go from the raw counters
to useful data, and without that exposing the raw stuff doesn't
seem that useful