Re: Consumers of libpmc/hwpmc

Hello Adrian,

I don't see anything after a quick search.  If you find a link to
the source, please send it my way.

At the moment the only breaking changes will affect users of the pmclog
APIs.
 - Andre has a diff up to fix the timestamp (this change's libpmc's
pmclog_read but not the kernel interface).  This was a half baked feature
that never worked as documented and it's unclear anyone is using it.
 - I plan to change map-in/out pmclog events to report all map in/out
events and extend the fields to report the length, file offset and flags.
We see some PCs that nobody seems to resolve correctly into a symbol, with
IBS we now care about the address of the load or store, and this makes it
easier for tools to lazily pull in elf info.
 - I also plan to add a header with information that I need for analysis
tools (e.g. cpuid, numa topology).

Existing tools also might want to make some changes for the following for
new types of counters.
 - GET_CAPS, domain and system-wide uncore counters
 - Multipart payloads that allow extra information to be added to the
callchain (AMD IBS) uses this.

I have a new framework/analysis passes for working with existing PMC data
and the new AMD IBS bits I wrote.  Eventually I'd like to see these hooked
up to Intel PEBS and ARM PT as well.

Best,
Ali


On Fri, Mar 20, 2026 at 10:27 AM Adrian Chadd <[email protected]> wrote:

> there are some, i'm tinkering with something from sandvine (whose name
> escapes me, even though I was tinkering with it two weeks ago!)
>
> What core changes are you thinking about?
>
> IMHO i think it'd be fine to break api a bit after such a long time
> being stale..
>
>
>
> -adrian
>
> On Thu, 19 Mar 2026 at 14:46, Ali Mashtizadeh <[email protected]>
> wrote:
> >
> > Hello everyone,
> >
> > I've been doing a lot of work on improving pmc/hwpmc on AMD systems but
> we need to make a few improvements to the pmc core.
> >
> > To be aware of compatibility issues, I was wondering if there are any
> 3rd party consumers of libpmc/hwpmc outside of PAPI and AMDuProf?
> >
> > Best,
> > Ali
>