[PATCH v12 0/8] Add support for EU stall sampling

Wed Feb 26 02:34:04 UTC 2025

On Tue, 25 Feb 2025 17:47:04 -0800, Harish Chegondi wrote:
>
> The following patch series add support for EU stall sampling,
> a new hardware feature first added in PVC and is being supported
> in XE2 and later architecture GPUs. This feature would enable
> capturing of EU stall data which include the IP address of the
> instruction stalled and various stall reason counts.
>
> Support for this feature is being added into Mesa:
> https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30142
>
> New IGT tests for EU stall sampling are being added:
> https://patchwork.freedesktop.org/series/143030/
>
> This patch series has undergone basic testing with the new IGT tests.
>
> Issues that need investigation:
> 1. Blocked reads with small user buffers may be blocked even with EU
> stall data in the kernel buffer as a previous read has set pollin to
> false even when kernel buffer has data that could be read but the user
> buffer is too small to read all the data.

The series is now completey reviewed. Planning to merge this once CI
completes on this version:

Reviewed-by: Ashutosh Dixit <ashutosh.dixit at intel.com>

>
> Thank You.
>
> v12 a. Move check for EU stall support to a header file
>     b. Move 'goto exit_drop;' to the next if statement
> v11 a. Lock optimization
>     b. Moved around code as per review feedback
> v10 a. Fixed error rewinding code
>     b. Used cancel_delayed_work_sync() instead of flush_delayed_work()
>     c. Replaced per xecore lock with a lock for all the xecore buffers
>     d. Remove function description for static functions.
>     e. Use extension number while parsing chain of extensions.
>     f. Moved code around as per review feedback
> v9: a. Split the big patch in v8 into two patches
>     b. Moved all drop data handling code into one patch
>     c. Several other code improvements as mentioned in the patches
> v8: a. Used div_u64() instead of / to fix 32-bit build issue.
>     b. Changed copyright year in new files to 2025.
>     c. Renamed struct drm_xe_eu_stall_data_pvc to struct xe_eu_stall_data_pvc
>     d. Renamed struct drm_xe_eu_stall_data_xe2 to struct xe_eu_stall_data_xe2
>
> v7: a. Renamed input property DRM_XE_EU_STALL_PROP_EVENT_REPORT_COUNT
>        to DRM_XE_EU_STALL_PROP_WAIT_NUM_REPORTS to be consistent with
>        OA. Renamed the corresponding internal variables.
>     b. Fixed some commit messages based on review feedback.
>     c. Changed sampling_rates from a pointer to flexible array.
>
> v6: a. Changed the uAPI input to accept sampling rate in GPU cycles
>        instead of sampling rate multiplier.
>     b. Fix buffer wrap around over write bug (Matt Olson).
>     c. Include EU stall sampling rates information and per XeCore buffer size in the query information.
>
> v5: Addressed review feedback from v4 including
>     a. Removed DRM_XE_EU_STALL_PROP_POLL_PERIOD from the uAPI (Ashutosh)
>     b. Separated the patches for Xe_HPC and Xe2 (Matt R)
>     c. Moved read() returning -EIO into a separate patch
>     d. Removed spinlocks around set_bit() and clear_bit() (Matt R)
>     e. Renamed several variables, structures and enums (Ashutosh and
> Matt R)
>     f. Addressed other review feedback.
> v4: Addressed review feedback from v3 including
>     a. Split the patch into multiple patches (Matt R)
>     b. Added a new device query to get EU stall info (Ashutosh)
>     c. Renamed all Dss to xecore (Matt R)
>     d. Removed buffer size and disable at open input properties. (Matt R)
>     e. Removed the "_SHIFT" macros (Matt R)
>     f. Allocate the EU stall buffer only on system memory.
>     g. Changed the work arounds to OOB (Matt R)
>     h. Other review feedback.
> v3: a. Removed data header and changed read() to return -EIO when data is dropped by the HW.
>     b. Added a new DRM_XE_OBSERVATION_IOCTL_INFO to query EU stall data record info
>     c. Added struct drm_xe_eu_stall_data_pvc and struct drm_xe_eu_stall_data_xe2
>        to xe_drm.h. These declarations would help user space to parse the
>        EU stall data
>     d. Addressed other review comments from v2
> v2: Rename xe perf layer as xe observation layer (Ashutosh)
>
> Test-with: cover.1739901972.git.harish.chegondi at intel.com
>
> Reviewed-by: Ben Olson <matthew.olson at intel.com>
> Acked-by: Felix Degrood <felix.j.degrood at intel.com>
> Signed-off-by: Harish Chegondi <harish.chegondi at intel.com>
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
>
> Harish Chegondi (8):
>   drm/xe/topology: Add a function to find the index of the last enabled
>     DSS in a mask
>   drm/xe/uapi: Introduce API for EU stall sampling
>   drm/xe/eustall: Add support to init, enable and disable EU stall
>     sampling
>   drm/xe/eustall: Add support to read() and poll() EU stall data
>   drm/xe/eustall: Add support to handle dropped EU stall data
>   drm/xe/eustall: Add EU stall sampling support for Xe2
>   drm/xe/uapi: Add a device query to get EU stall sampling information
>   drm/xe/eustall: Add workaround 22016596838 which applies to PVC.
>
>  drivers/gpu/drm/xe/Makefile                |   1 +
>  drivers/gpu/drm/xe/regs/xe_eu_stall_regs.h |  29 +
>  drivers/gpu/drm/xe/xe_eu_stall.c           | 960 +++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_eu_stall.h           |  24 +
>  drivers/gpu/drm/xe/xe_gt.c                 |   5 +
>  drivers/gpu/drm/xe/xe_gt_topology.h        |  13 +
>  drivers/gpu/drm/xe/xe_gt_types.h           |   3 +
>  drivers/gpu/drm/xe/xe_observation.c        |  14 +
>  drivers/gpu/drm/xe/xe_query.c              |  43 +
>  drivers/gpu/drm/xe/xe_trace.h              |  30 +
>  drivers/gpu/drm/xe/xe_wa_oob.rules         |   1 +
>  include/uapi/drm/xe_drm.h                  |  74 ++
>  12 files changed, 1197 insertions(+)
>  create mode 100644 drivers/gpu/drm/xe/regs/xe_eu_stall_regs.h
>  create mode 100644 drivers/gpu/drm/xe/xe_eu_stall.c
>  create mode 100644 drivers/gpu/drm/xe/xe_eu_stall.h
>
> --
> 2.48.1
>