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    SubjectRe: [Freedreno] [PATCH v2 0/2] drm: fdinfo memory stats
    On Tue, Apr 11, 2023 at 10:36 AM Dmitry Baryshkov
    <dmitry.baryshkov@linaro.org> wrote:
    >
    > On Tue, 11 Apr 2023 at 20:13, Rob Clark <robdclark@gmail.com> wrote:
    > >
    > > On Tue, Apr 11, 2023 at 9:53 AM Daniel Vetter <daniel@ffwll.ch> wrote:
    > > >
    > > > On Tue, Apr 11, 2023 at 09:47:32AM -0700, Rob Clark wrote:
    > > > > On Mon, Apr 10, 2023 at 2:06 PM Rob Clark <robdclark@gmail.com> wrote:
    > > > > >
    > > > > > From: Rob Clark <robdclark@chromium.org>
    > > > > >
    > > > > > Similar motivation to other similar recent attempt[1]. But with an
    > > > > > attempt to have some shared code for this. As well as documentation.
    > > > > >
    > > > > > It is probably a bit UMA-centric, I guess devices with VRAM might want
    > > > > > some placement stats as well. But this seems like a reasonable start.
    > > > > >
    > > > > > Basic gputop support: https://patchwork.freedesktop.org/series/116236/
    > > > > > And already nvtop support: https://github.com/Syllo/nvtop/pull/204
    > > > >
    > > > > On a related topic, I'm wondering if it would make sense to report
    > > > > some more global things (temp, freq, etc) via fdinfo? Some of this,
    > > > > tools like nvtop could get by trawling sysfs or other driver specific
    > > > > ways. But maybe it makes sense to have these sort of things reported
    > > > > in a standardized way (even though they aren't really per-drm_file)
    > > >
    > > > I think that's a bit much layering violation, we'd essentially have to
    > > > reinvent the hwmon sysfs uapi in fdinfo. Not really a business I want to
    > > > be in :-)
    > >
    > > I guess this is true for temp (where there are thermal zones with
    > > potentially multiple temp sensors.. but I'm still digging my way thru
    > > the thermal_cooling_device stuff)
    >
    > It is slightly ugly. All thermal zones and cooling devices are virtual
    > devices (so, even no connection to the particular tsens device). One
    > can either enumerate them by checking
    > /sys/class/thermal/thermal_zoneN/type or enumerate them through
    > /sys/class/hwmon. For cooling devices again the only enumeration is
    > through /sys/class/thermal/cooling_deviceN/type.
    >
    > Probably it should be possible to push cooling devices and thermal
    > zones under corresponding providers. However I do not know if there is
    > a good way to correlate cooling device (ideally a part of GPU) to the
    > thermal_zone (which in our case is provided by tsens / temp_alarm
    > rather than GPU itself).
    >
    > >
    > > But what about freq? I think, esp for cases where some "fw thing" is
    > > controlling the freq we end up needing to use gpu counters to measure
    > > the freq.
    >
    > For the freq it is slightly easier: /sys/class/devfreq/*, devices are
    > registered under proper parent (IOW, GPU). So one can read
    > /sys/class/devfreq/3d00000.gpu/cur_freq or
    > /sys/bus/platform/devices/3d00000.gpu/devfreq/3d00000.gpu/cur_freq.
    >
    > However because of the components usage, there is no link from
    > /sys/class/drm/card0
    > (/sys/devices/platform/soc@0/ae00000.display-subsystem/ae01000.display-controller/drm/card0)
    > to /sys/devices/platform/soc@0/3d00000.gpu, the GPU unit.
    >
    > Getting all these items together in a platform-independent way would
    > be definitely an important but complex topic.

    But I don't believe any of the pci gpu's use devfreq ;-)

    And also, you can't expect the CPU to actually know the freq when fw
    is the one controlling freq. We can, currently, have a reasonable
    approximation from devfreq but that stops if IFPC is implemented. And
    other GPUs have even less direct control. So freq is a thing that I
    don't think we should try to get from "common frameworks"

    BR,
    -R

    > >
    > > > What might be needed is better glue to go from the fd or fdinfo to the
    > > > right hw device and then crawl around the hwmon in sysfs automatically. I
    > > > would not be surprised at all if we really suck on this, probably more
    > > > likely on SoC than pci gpus where at least everything should be under the
    > > > main pci sysfs device.
    > >
    > > yeah, I *think* userspace would have to look at /proc/device-tree to
    > > find the cooling device(s) associated with the gpu.. at least I don't
    > > see a straightforward way to figure it out just for sysfs
    > >
    > > BR,
    > > -R
    > >
    > > > -Daniel
    > > >
    > > > >
    > > > > BR,
    > > > > -R
    > > > >
    > > > >
    > > > > > [1] https://patchwork.freedesktop.org/series/112397/
    > > > > >
    > > > > > Rob Clark (2):
    > > > > > drm: Add fdinfo memory stats
    > > > > > drm/msm: Add memory stats to fdinfo
    > > > > >
    > > > > > Documentation/gpu/drm-usage-stats.rst | 21 +++++++
    > > > > > drivers/gpu/drm/drm_file.c | 79 +++++++++++++++++++++++++++
    > > > > > drivers/gpu/drm/msm/msm_drv.c | 25 ++++++++-
    > > > > > drivers/gpu/drm/msm/msm_gpu.c | 2 -
    > > > > > include/drm/drm_file.h | 10 ++++
    > > > > > 5 files changed, 134 insertions(+), 3 deletions(-)
    > > > > >
    > > > > > --
    > > > > > 2.39.2
    > > > > >
    > > >
    > > > --
    > > > Daniel Vetter
    > > > Software Engineer, Intel Corporation
    > > > http://blog.ffwll.ch
    >
    >
    >
    > --
    > With best wishes
    > Dmitry

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