95 lines
2.7 KiB
ReStructuredText
95 lines
2.7 KiB
ReStructuredText
=======================================
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Peak Tops Limiter (PTL) sysfs Interface
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=======================================
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Overview
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--------
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The Peak Tops Limiter (PTL) sysfs interface enables users to control and
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configure the PTL feature for each GPU individually. All PTL-related
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sysfs files are located under `/sys/class/drm/cardX/device/ptl/`, where
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`X` is the GPU index. Through these files, users can enable or disable
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PTL, set preferred data formats, and query supported formats for each GPU.
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PTL sysfs files
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----------------
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The following files are available under `/sys/class/drm/cardX/device/ptl/`:
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- `ptl_enable`
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- `ptl_format`
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- `ptl_supported_formats`
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PTL Enable/Disable
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------------------
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File: `ptl_enable`
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Type: Read/Write (rw)
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Read: Returns the current PTL status as a string: `enabled` if PTL
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is active, or `disabled` if inactive.
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Write:
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- Write `1` or `enabled` to enable PTL
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- Write `0` or `disabled` to disable PTL
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Examples::
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# Query PTL status
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cat /sys/class/drm/card1/device/ptl/ptl_enable
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# Output: enabled
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# Enable PTL
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sudo bash -c "echo 1 > /sys/class/drm/card1/device/ptl/ptl_enable"
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# Disable PTL
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sudo bash -c "echo 0 > /sys/class/drm/card1/device/ptl/ptl_enable"
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PTL Format (Preferred Data Formats)
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-----------------------------------
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File: `ptl_format`
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Type: Read/Write (rw)
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Read: Returns the two preferred formats, e.g. `I8,F32`.
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Write: Accepts two formats separated by a comma, e.g. `I8,F32`.
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- Both formats must be supported and different.
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- If an invalid format is provided (not supported, or both formats are the
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same), the driver will return "write error: Invalid argument".
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Examples::
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# Query PTL formats
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cat /sys/class/drm/card1/device/ptl/ptl_format
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# Output: I8,F32
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# Set PTL formats
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sudo bash -c "echo I8,F32 > /sys/class/drm/card1/device/ptl/ptl_format"
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Supported Formats
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-----------------
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File: `ptl_supported_formats`
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Type: Read-only (r)
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Read: Returns a comma-separated list of supported formats, e.g.
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`I8,F16,BF16,F32,F64`.
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Example::
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# Check supported formats
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cat /sys/class/drm/card1/device/ptl/ptl_supported_formats
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# Output: I8,F16,BF16,F32,F64
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Behavioral Notes
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----------------
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- PTL formats can only be set when PTL is enabled.
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- If PTL is disabled, `ptl_format` returns `N/A`.
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- Only two formats can be set at a time, and they must be from the supported set and different..
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- All commands support per-GPU targeting.
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- Root permission is required to enable/disable PTL or change formats.
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- If the hardware does not support PTL, the PTL sysfs directory will not
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be created.
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Implementation
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--------------
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The PTL sysfs nodes are implemented in `drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c`.
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