1.. _drm-client-usage-stats: 2 3====================== 4DRM client usage stats 5====================== 6 7DRM drivers can choose to export partly standardised text output via the 8`fops->show_fdinfo()` as part of the driver specific file operations registered 9in the `struct drm_driver` object registered with the DRM core. 10 11One purpose of this output is to enable writing as generic as practicaly 12feasible `top(1)` like userspace monitoring tools. 13 14Given the differences between various DRM drivers the specification of the 15output is split between common and driver specific parts. Having said that, 16wherever possible effort should still be made to standardise as much as 17possible. 18 19File format specification 20========================= 21 22- File shall contain one key value pair per one line of text. 23- Colon character (`:`) must be used to delimit keys and values. 24- All keys shall be prefixed with `drm-`. 25- Whitespace between the delimiter and first non-whitespace character shall be 26 ignored when parsing. 27- Neither keys or values are allowed to contain whitespace characters. 28- Numerical key value pairs can end with optional unit string. 29- Data type of the value is fixed as defined in the specification. 30 31Key types 32--------- 33 341. Mandatory, fully standardised. 352. Optional, fully standardised. 363. Driver specific. 37 38Data types 39---------- 40 41- <uint> - Unsigned integer without defining the maximum value. 42- <str> - String excluding any above defined reserved characters or whitespace. 43 44Mandatory fully standardised keys 45--------------------------------- 46 47- drm-driver: <str> 48 49String shall contain the name this driver registered as via the respective 50`struct drm_driver` data structure. 51 52Optional fully standardised keys 53-------------------------------- 54 55- drm-pdev: <aaaa:bb.cc.d> 56 57For PCI devices this should contain the PCI slot address of the device in 58question. 59 60- drm-client-id: <uint> 61 62Unique value relating to the open DRM file descriptor used to distinguish 63duplicated and shared file descriptors. Conceptually the value should map 1:1 64to the in kernel representation of `struct drm_file` instances. 65 66Uniqueness of the value shall be either globally unique, or unique within the 67scope of each device, in which case `drm-pdev` shall be present as well. 68 69Userspace should make sure to not double account any usage statistics by using 70the above described criteria in order to associate data to individual clients. 71 72- drm-engine-<str>: <uint> ns 73 74GPUs usually contain multiple execution engines. Each shall be given a stable 75and unique name (str), with possible values documented in the driver specific 76documentation. 77 78Value shall be in specified time units which the respective GPU engine spent 79busy executing workloads belonging to this client. 80 81Values are not required to be constantly monotonic if it makes the driver 82implementation easier, but are required to catch up with the previously reported 83larger value within a reasonable period. Upon observing a value lower than what 84was previously read, userspace is expected to stay with that larger previous 85value until a monotonic update is seen. 86 87- drm-engine-capacity-<str>: <uint> 88 89Engine identifier string must be the same as the one specified in the 90drm-engine-<str> tag and shall contain a greater than zero number in case the 91exported engine corresponds to a group of identical hardware engines. 92 93In the absence of this tag parser shall assume capacity of one. Zero capacity 94is not allowed. 95 96- drm-memory-<str>: <uint> [KiB|MiB] 97 98Each possible memory type which can be used to store buffer objects by the 99GPU in question shall be given a stable and unique name to be returned as the 100string here. 101 102Value shall reflect the amount of storage currently consumed by the buffer 103object belong to this client, in the respective memory region. 104 105Default unit shall be bytes with optional unit specifiers of 'KiB' or 'MiB' 106indicating kibi- or mebi-bytes. 107 108- drm-cycles-<str> <uint> 109 110Engine identifier string must be the same as the one specified in the 111drm-engine-<str> tag and shall contain the number of busy cycles for the given 112engine. 113 114Values are not required to be constantly monotonic if it makes the driver 115implementation easier, but are required to catch up with the previously reported 116larger value within a reasonable period. Upon observing a value lower than what 117was previously read, userspace is expected to stay with that larger previous 118value until a monotonic update is seen. 119 120- drm-maxfreq-<str> <uint> [Hz|MHz|KHz] 121 122Engine identifier string must be the same as the one specified in the 123drm-engine-<str> tag and shall contain the maximum frequency for the given 124engine. Taken together with drm-cycles-<str>, this can be used to calculate 125percentage utilization of the engine, whereas drm-engine-<str> only reflects 126time active without considering what frequency the engine is operating as a 127percentage of it's maximum frequency. 128 129=============================== 130Driver specific implementations 131=============================== 132 133:ref:`i915-usage-stats` 134