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/amdgpu/thermal.rst | 170 +++++++++++++++++++++++++++++++++++ 1 file changed, 170 insertions(+) create mode 100644 Documentation/gpu/amdgpu/thermal.rst (limited to 'Documentation/gpu/amdgpu/thermal.rst') diff --git a/Documentation/gpu/amdgpu/thermal.rst b/Documentation/gpu/amdgpu/thermal.rst new file mode 100644 index 000000000..1768a106a --- /dev/null +++ b/Documentation/gpu/amdgpu/thermal.rst @@ -0,0 +1,170 @@ +=========================================== + GPU Power/Thermal Controls and Monitoring +=========================================== + +HWMON Interfaces +================ + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: hwmon + +GPU sysfs Power State Interfaces +================================ + +GPU power controls are exposed via sysfs files. + +power_dpm_state +--------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: power_dpm_state + +power_dpm_force_performance_level +--------------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: power_dpm_force_performance_level + +pp_table +-------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_table + +pp_od_clk_voltage +----------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_od_clk_voltage + +pp_dpm_* +-------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_dpm_sclk pp_dpm_mclk pp_dpm_socclk pp_dpm_fclk pp_dpm_dcefclk pp_dpm_pcie + +pp_power_profile_mode +--------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pp_power_profile_mode + +pm_policy +--------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: pm_policy + +\*_busy_percent +--------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: gpu_busy_percent + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: mem_busy_percent + +gpu_metrics +----------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: gpu_metrics + +fan_curve +--------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: fan_curve + +acoustic_limit_rpm_threshold +---------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: acoustic_limit_rpm_threshold + +acoustic_target_rpm_threshold +----------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: acoustic_target_rpm_threshold + +fan_target_temperature +---------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: fan_target_temperature + +fan_minimum_pwm +--------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: fan_minimum_pwm + +fan_zero_rpm_enable +---------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: fan_zero_rpm_enable + +fan_zero_rpm_stop_temperature +----------------------------- + +.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c + :doc: fan_zero_rpm_stop_temperature + +GFXOFF +====== + +GFXOFF is a feature found in most recent GPUs that saves power at runtime. The +card's RLC (RunList Controller) firmware powers off the gfx engine +dynamically when there is no workload on gfx or compute pipes. GFXOFF is on by +default on supported GPUs. + +Userspace can interact with GFXOFF through a debugfs interface (all values in +`uint32_t`, unless otherwise noted): + +``amdgpu_gfxoff`` +----------------- + +Use it to enable/disable GFXOFF, and to check if it's current enabled/disabled:: + + $ xxd -l1 -p /sys/kernel/debug/dri/0/amdgpu_gfxoff + 01 + +- Write 0 to disable it, and 1 to enable it. +- Read 0 means it's disabled, 1 it's enabled. + +If it's enabled, that means that the GPU is free to enter into GFXOFF mode as +needed. Disabled means that it will never enter GFXOFF mode. + +``amdgpu_gfxoff_status`` +------------------------ + +Read it to check current GFXOFF's status of a GPU:: + + $ xxd -l1 -p /sys/kernel/debug/dri/0/amdgpu_gfxoff_status + 02 + +- 0: GPU is in GFXOFF state, the gfx engine is powered down. +- 1: Transition out of GFXOFF state +- 2: Not in GFXOFF state +- 3: Transition into GFXOFF state + +If GFXOFF is enabled, the value will be transitioning around [0, 3], always +getting into 0 when possible. When it's disabled, it's always at 2. Returns +``-EINVAL`` if it's not supported. + +``amdgpu_gfxoff_count`` +----------------------- + +Read it to get the total GFXOFF entry count at the time of query since system +power-up. The value is an `uint64_t` type, however, due to firmware limitations, +it can currently overflow as an `uint32_t`. *Only supported in vangogh* + +``amdgpu_gfxoff_residency`` +--------------------------- + +Write 1 to amdgpu_gfxoff_residency to start logging, and 0 to stop. Read it to +get average GFXOFF residency % multiplied by 100 during the last logging +interval. E.g. a value of 7854 means 78.54% of the time in the last logging +interval the GPU was in GFXOFF mode. *Only supported in vangogh* -- cgit v1.3.1