Re: [PATCH 00/13] drm/msm: Add PERFCNTR_CONFIG ioctl

[Rob Clark <rob.clark@oss.qualcomm.com>]

On Tue, Apr 21, 2026 at 6:54 PM Dmitry Baryshkov
<dmitry.baryshkov@oss.qualcomm.com> wrote:
>
> On Mon, Apr 20, 2026 at 03:25:22PM -0700, Rob Clark wrote:
> > Add a new PERFCNTR_CONFIG ioctl, serving two functions:
> >
> > 1. Global counter collection (restricted to perfmon_capable()) using the
> >    MSM_PERFCNTR_STREAM flag.  Global counter sampling is, global, across
> >    contexts.  Only a single global counter stream is allowed at a time.
> > 2. Reserve counters for local counter collection.  Local counter
> >    collection is local to a cmdstream (GEM_SUBMIT), and as such is
> >    allowed in all processes without additional privileges.
> >
> > The kernel enforces that counters assigned for global counter collection
> > do not conflict with counters reserved for local counter collection, and
> > visa versa.  Since local counter collection is scoped to a single cmd-
> > stream, multiple UMD processes can overlap in their reserved counters.
> > But cannot conflict with global counter usage.
> >
> > In the case of local counter collection, the UMD is still responsible
> > for programming the corresponding SELect registers, and sampling the
> > counter values, from it's cmdstream.  But by performing the reservation
> > step, the UMD protects itself from the kernel trying to use the same
> > SEL/counter regs for global counter collection.
> >
> > For global counter collection, the kernel programs SEL regs, and sets up
> > a timer for counter sampling.  Userspace reads out the sampled values
> > from the returned perfcntr stream fd.  Releasing the global perfcntr
> > stream is simply a matter of close()ing the fd.
> >
> > Since the counter sampling is done in the kernel, this prepares us for
> > not having to disable IFPC while global counter sampling is active.  But
> > wiring this up will come in a later patch.
> >
> > The mesa side of this is at:
> > https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40522
> >
> > Rob Clark (13):
> >   drm/msm: Remove obsolete perf infrastructure
> >   drm/msm/adreno: Sync registers from mesa
> >   drm/msm/registers: Sync gen_header.py from mesa
> >   drm/msm/registers: Add perfcntr json
> >   drm/msm: Allow CAP_PERFMON for setting SYSPROF
> >   drm/msm: Add a6xx+ perfcntr tables
> >   drm/msm: Add sysprof accessors
> >   drm/msm/a6xx: Add yield & flush helper
> >   drm/msm: Add per-context perfcntr state
> >   drm/msm: Add basic perfcntr infrastructure
> >   drm/msm/a6xx+: Add support to configure perfcntrs
> >   drm/msm/a8xx: Add perfcntr flush sequence
> >   drm/msm: Add PERFCNTR_CONFIG ioctl
> >
> The series doesn't apply to linux-next. Please switch to b4 and use b4
> --edit-deps to specify dependencies.

fwiw 20260411150312.257937-1-robin.clark@oss.qualcomm.com is the thing
missing from linux-next

BR,
-R