From: Tvrtko Ursulin tvrtko.ursulin@intel.com
Proposal to standardise the fdinfo text format as optionally output by DRM drivers.
Idea is that a simple but, well defined, spec will enable generic userspace tools to be written while at the same time avoiding a more heavy handed approach of adding a mid-layer to DRM.
i915 implements a subset of the spec, everything apart from the memory stats currently, and a matching intel_gpu_top tool exists.
Open is to see if AMD can migrate to using the proposed GPU utilisation key-value pairs, or if they are not workable to see whether to go vendor specific, or if a standardised alternative can be found which is workable for both drivers.
Same for the memory utilisation key-value pairs proposal.
v2: * Update for removal of name and pid.
Signed-off-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Cc: David M Nieto David.Nieto@amd.com Cc: Christian König christian.koenig@amd.com Cc: Daniel Vetter daniel@ffwll.ch --- Documentation/gpu/drm-usage-stats.rst | 97 +++++++++++++++++++++++++++ Documentation/gpu/index.rst | 1 + 2 files changed, 98 insertions(+) create mode 100644 Documentation/gpu/drm-usage-stats.rst
diff --git a/Documentation/gpu/drm-usage-stats.rst b/Documentation/gpu/drm-usage-stats.rst new file mode 100644 index 000000000000..78dc01c30e22 --- /dev/null +++ b/Documentation/gpu/drm-usage-stats.rst @@ -0,0 +1,97 @@ +.. _drm-client-usage-stats: + +====================== +DRM client usage stats +====================== + +DRM drivers can choose to export partly standardised text output via the +`fops->show_fdinfo()` as part of the driver specific file operations registered +in the `struct drm_driver` object registered with the DRM core. + +One purpose of this output is to enable writing as generic as practicaly +feasible `top(1)` like userspace monitoring tools. + +Given the differences between various DRM drivers the specification of the +output is split between common and driver specific parts. Having said that, +wherever possible effort should still be made to standardise as much as +possible. + +File format specification +========================= + +- File shall contain one key value pair per one line of text. +- Colon character (`:`) must be used to delimit keys and values. +- All keys shall be prefixed with `drm-`. +- Whitespace between the delimiter and first non-whitespace character shall be + ignored when parsing. +- Neither keys or values are allowed to contain whitespace characters. +- Numerical key value pairs can end with optional unit string. +- Data type of the value is fixed as defined in the specification. + +Key types +--------- + +1. Mandatory, fully standardised. +2. Optional, fully standardised. +3. Driver specific. + +Data types +---------- + +- <uint> - Unsigned integer without defining the maximum value. +- <str> - String excluding any above defined reserved characters or whitespace. + +Mandatory fully standardised keys +--------------------------------- + +- drm-driver: <str> + +String shall contain a fixed string uniquely identified the driver handling +the device in question. For example name of the respective kernel module. + +Optional fully standardised keys +-------------------------------- + +- drm-pdev: aaaa:bb.cc.d + +For PCI devices this should contain the PCI slot address of the device in +question. + +- drm-client-id: <uint> + +Unique value relating to the open DRM file descriptor used to distinguish +duplicated and shared file descriptors. Conceptually the value should map 1:1 +to the in kernel representation of `struct drm_file` instances. + +Uniqueness of the value shall be either globally unique, or unique within the +scope of each device, in which case `drm-pdev` shall be present as well. + +Userspace should make sure to not double account any usage statistics by using +the above described criteria in order to associate data to individual clients. + +- drm-engine-<str>: <uint> ns + +GPUs usually contain multiple execution engines. Each shall be given a stable +and unique name (str), with possible values documented in the driver specific +documentation. + +Value shall be in specified time units which the respective GPU engine spent +busy executing workloads belonging to this client. + +Values are not required to be constantly monotonic if it makes the driver +implementation easier, but are required to catch up with the previously reported +larger value within a reasonable period. Upon observing a value lower than what +was previously read, userspace is expected to stay with that larger previous +value until a monotonic update is seen. + +- drm-memory-<str>: <uint> [KiB|MiB] + +Each possible memory type which can be used to store buffer objects by the +GPU in question shall be given a stable and unique name to be returned as the +string here. + +Value shall reflect the amount of storage currently consumed by the buffer +object belong to this client, in the respective memory region. + +Default unit shall be bytes with optional unit specifiers of 'KiB' or 'MiB' +indicating kibi- or mebi-bytes. diff --git a/Documentation/gpu/index.rst b/Documentation/gpu/index.rst index b9c1214d8f23..b99dede9a5b1 100644 --- a/Documentation/gpu/index.rst +++ b/Documentation/gpu/index.rst @@ -10,6 +10,7 @@ Linux GPU Driver Developer's Guide drm-kms drm-kms-helpers drm-uapi + drm-usage-stats driver-uapi drm-client drivers