[libcamera-devel] [PATCH 0/1] Use tracing with perfetto in ChromeOS

[Cheng-Hao Yang]

Uploaded PATCH v2. Descriptions and instructions are added in the document:
tracing.rst. Please check :)
I don't know how to split up the patch elegantly though...

> It would be nice if we could avoid maintaining different tracing
frameworks. My main issue with perfetto is that it's not packaged by
distributions, making it hard to use outside of Chrome OS and Android.
Yeah, that's an issue... The source of truth is in aosp, and it was meant
to support Android/Chromium in the first place IIUC...

BR,
Harvey

On Wed, Jul 20, 2022 at 6:38 PM Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:

> On Wed, Jul 20, 2022 at 04:57:22PM +0800, Cheng-Hao Yang wrote:
> > Hi Laurent,
> >
> > > Do you know if there's an easy way to try perfetto on a non-Chrome OS
> > (and non-Android) device ?
> > I haven't tried it myself, but on the Perfetto Docs, there are
> instructions
> > to capture a trace on Linux [1]. I'm not sure what kind of traces you'd
> get
> > though :)
> >
> > Do you mean that we might consider using perfetto in libcamera, not only
> on
> > ChromeOS devices?
>
> It would be nice if we could avoid maintaining different tracing
> frameworks. My main issue with perfetto is that it's not packaged by
> distributions, making it hard to use outside of Chrome OS and Android.
>
> > With a trace result (like I attached in the last message) though, we can
> > see the visualized result on any devices with a browser, FYI.
> >
> > [1]: https://perfetto.dev/docs/quickstart/linux-tracing
> >
> > On Wed, Jul 20, 2022 at 4:49 PM Laurent Pinchart wrote:
> > > On Tue, Jul 19, 2022 at 05:20:56PM +0800, Cheng-Hao Yang via
> libcamera-devel wrote:
> > > > Hi Kieran,
> > > >
> > > > Thanks for looking into this! I'll add more description/instructions
> in the
> > > > README, including adding new tracing points and how to check the
> tracing
> > > > result.
> > >
> > > Thank you.
> > >
> > > > In the meantime, you can try https://ui.perfetto.dev with the
> attached
> > > > tracing result I recorded. In the "Show timeline" tab, you can see
> that
> > > > there are quite some traces with Category "libcamera "in
> CameraModuleThr 9
> > > > & CameraDeviceOps 11. Those might be helpful when we need to debug
> > > > something :)
> > >
> > > Do you know if there's an easy way to try perfetto on a non-Chrome OS
> > > (and non-Android) device ?
> > >
> > > > On Mon, Jul 18, 2022 at 7:49 PM Kieran Bingham wrote:
> > > > > Quoting Harvey Yang via libcamera-devel (2022-06-15 15:20:50)
> > > > > > Hello everyone,
> > > > > >
> > > > > > This is the first draft of the patch(es) that uses tracing with
> perfetto
> > > > > > instead of lttng when libcamera is used in ChromeOS, which
> already uses
> > > > > > perfetto to collect traces in most of the applications/services.
> > > > > >
> > > > > > Please take a look and see if it's the right direction to go.
> Mostly I
> > > > > > copied and pasted the simple producer in chromiumos (also
> written by
> > > > > > me :) ):
> > > > > >
> > > > > >
> https://chromium.googlesource.com/chromiumos/platform2/+/HEAD/perfetto_simple_producer
> > > > > >
> > > > >
> > > > > This looks interesting, and the perfetto UI viewer tool [0] looks
> good too.
> > > > >
> > > > > [0] https://ui.perfetto.dev/
> > > > >
> > > > > Could you summarise some instructions on how to test this please?
> > > > > A good visualisation for libcamera internals would be great. I
> would
> > > > > love to see this able to switch between showing what each thread /
> > > > > component is busy processing, or have the timeline present the
> progress
> > > > > of Requests through the system.
> > > > >
> > > > > > Harvey Yang (1):
> > > > > >   Use tracing with perfetto in ChromeOS
> > > > > >
> > > > > >  include/libcamera/internal/tracepoints.h.in   | 37 +++++++++--
> > > > > >  .../internal/tracepoints/meson.build          | 25 ++++---
> > > > > >  .../internal/tracepoints/pipeline.perfetto    | 10 +++
> > > > > >  .../internal/tracepoints/request.perfetto     | 30 +++++++++
> > > > > >  meson.build                                   |  1 +
> > > > > >  src/android/cros/camera3_hal.cpp              |  5 ++
> > > > > >  src/android/cros/meson.build                  |  1 +
> > > > > >  src/libcamera/meson.build                     | 18 ++++-
> > > > > >  src/libcamera/pipeline_perfetto.cpp           | 22 +++++++
> > > > > >  src/libcamera/request_perfetto.cpp            | 65
> +++++++++++++++++++
> > > > > >  src/libcamera/tracepoints.cpp                 | 11 ++++
> > > > > >  11 files changed, 209 insertions(+), 16 deletions(-)
> > > > > >  create mode 100644
> include/libcamera/internal/tracepoints/pipeline.perfetto
> > > > > >  create mode 100644
> include/libcamera/internal/tracepoints/request.perfetto
> > > > > >  create mode 100644 src/libcamera/pipeline_perfetto.cpp
> > > > > >  create mode 100644 src/libcamera/request_perfetto.cpp
>
> --
> Regards,
>
> Laurent Pinchart
>
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