From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- Documentation/gpu/imagination/index.rst | 13 +++ Documentation/gpu/imagination/uapi.rst | 171 ++++++++++++++++++++++++++++++++ 2 files changed, 184 insertions(+) create mode 100644 Documentation/gpu/imagination/index.rst create mode 100644 Documentation/gpu/imagination/uapi.rst (limited to 'Documentation/gpu/imagination') diff --git a/Documentation/gpu/imagination/index.rst b/Documentation/gpu/imagination/index.rst new file mode 100644 index 000000000..0c1e247ce --- /dev/null +++ b/Documentation/gpu/imagination/index.rst @@ -0,0 +1,13 @@ +======================================= +drm/imagination PowerVR Graphics Driver +======================================= + +.. kernel-doc:: drivers/gpu/drm/imagination/pvr_drv.c + :doc: PowerVR (Series 6 and later) and IMG Graphics Driver + +Contents +======== +.. toctree:: + :maxdepth: 2 + + uapi diff --git a/Documentation/gpu/imagination/uapi.rst b/Documentation/gpu/imagination/uapi.rst new file mode 100644 index 000000000..7502413d0 --- /dev/null +++ b/Documentation/gpu/imagination/uapi.rst @@ -0,0 +1,171 @@ +==== +UAPI +==== +The sources associated with this section can be found in ``pvr_drm.h``. + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR UAPI + +OBJECT ARRAYS +============= +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_obj_array + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: DRM_PVR_OBJ_ARRAY + +IOCTLS +====== +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL interface + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: PVR_IOCTL + +DEV_QUERY +--------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL DEV_QUERY interface + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_dev_query + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_dev_query_args + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_dev_query_gpu_info + drm_pvr_dev_query_runtime_info + drm_pvr_dev_query_hwrt_info + drm_pvr_dev_query_quirks + drm_pvr_dev_query_enhancements + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_heap_id + drm_pvr_heap + drm_pvr_dev_query_heap_info + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_static_data_area_usage + drm_pvr_static_data_area + drm_pvr_dev_query_static_data_areas + +CREATE_BO +--------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL CREATE_BO interface + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_create_bo_args + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: Flags for CREATE_BO + +GET_BO_MMAP_OFFSET +------------------ +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL GET_BO_MMAP_OFFSET interface + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_get_bo_mmap_offset_args + +CREATE_VM_CONTEXT and DESTROY_VM_CONTEXT +---------------------------------------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL CREATE_VM_CONTEXT and DESTROY_VM_CONTEXT interfaces + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_create_vm_context_args + drm_pvr_ioctl_destroy_vm_context_args + +VM_MAP and VM_UNMAP +------------------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL VM_MAP and VM_UNMAP interfaces + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_vm_map_args + drm_pvr_ioctl_vm_unmap_args + +CREATE_CONTEXT and DESTROY_CONTEXT +---------------------------------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL CREATE_CONTEXT and DESTROY_CONTEXT interfaces + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_create_context_args + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ctx_priority + drm_pvr_ctx_type + drm_pvr_static_render_context_state + drm_pvr_static_render_context_state_format + drm_pvr_reset_framework + drm_pvr_reset_framework_format + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_destroy_context_args + +CREATE_FREE_LIST and DESTROY_FREE_LIST +-------------------------------------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL CREATE_FREE_LIST and DESTROY_FREE_LIST interfaces + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_create_free_list_args + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_destroy_free_list_args + +CREATE_HWRT_DATASET and DESTROY_HWRT_DATASET +-------------------------------------------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL CREATE_HWRT_DATASET and DESTROY_HWRT_DATASET interfaces + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_create_hwrt_dataset_args + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_create_hwrt_geom_data_args + drm_pvr_create_hwrt_rt_data_args + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_destroy_hwrt_dataset_args + +SUBMIT_JOBS +----------- +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: PowerVR IOCTL SUBMIT_JOBS interface + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: Flags for the drm_pvr_sync_op object. + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_ioctl_submit_jobs_args + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: Flags for SUBMIT_JOB ioctl geometry command. + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: Flags for SUBMIT_JOB ioctl fragment command. + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: Flags for SUBMIT_JOB ioctl compute command. + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :doc: Flags for SUBMIT_JOB ioctl transfer command. + +.. kernel-doc:: include/uapi/drm/pvr_drm.h + :identifiers: drm_pvr_sync_op + drm_pvr_job_type + drm_pvr_hwrt_data_ref + drm_pvr_job + +Internal notes +============== +.. kernel-doc:: drivers/gpu/drm/imagination/pvr_device.h + :doc: IOCTL validation helpers + +.. kernel-doc:: drivers/gpu/drm/imagination/pvr_device.h + :identifiers: PVR_STATIC_ASSERT_64BIT_ALIGNED PVR_IOCTL_UNION_PADDING_CHECK + pvr_ioctl_union_padding_check -- cgit v1.3.1