[PATCH] drm/i915/pmu: Drop custom hotplug code
Lucas De Marchi
lucas.demarchi at intel.com
Thu Jan 23 16:27:29 UTC 2025
On Thu, Jan 23, 2025 at 09:43:35AM +0000, Tvrtko Ursulin wrote:
>
>On 20/01/2025 22:57, Lucas De Marchi wrote:
>>On Mon, Jan 20, 2025 at 10:08:39AM -0500, Liang, Kan wrote:
>>>
>>>
>>>On 2025-01-16 5:24 p.m., Lucas De Marchi wrote:
>>>>Since commit 4ba4f1afb6a9 ("perf: Generic hotplug support for a PMU with
>>>>a scope"), there's generic support for system-wide counters and
>>>>integration with cpu hotplug. Set our scope to PERF_PMU_SCOPE_SYS_WIDE
>>>>instead of all the boilerplate code for handling hotplug.
>>>>
>>>>Cc: Kan Liang <kan.liang at linux.intel.com>
>>>>Cc: Peter Zijlstra (Intel) <peterz at infradead.org>
>>>>Cc: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
>>>>Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
>>>>---
>>>> drivers/gpu/drm/i915/i915_module.c | 2 -
>>>> drivers/gpu/drm/i915/i915_pmu.c | 114 +----------------------------
>>>> drivers/gpu/drm/i915/i915_pmu.h | 11 ---
>>>> 3 files changed, 1 insertion(+), 126 deletions(-)
>>>>
>>>>diff --git a/drivers/gpu/drm/i915/i915_module.c
>>>>b/drivers/gpu/drm/i915/i915_module.c
>>>>index 7ed6d70389af9..7affe07f84f45 100644
>>>>--- a/drivers/gpu/drm/i915/i915_module.c
>>>>+++ b/drivers/gpu/drm/i915/i915_module.c
>>>>@@ -71,8 +71,6 @@ static const struct {
>>>> { .init = i915_vma_resource_module_init,
>>>> .exit = i915_vma_resource_module_exit },
>>>> { .init = i915_mock_selftests },
>>>>- { .init = i915_pmu_init,
>>>>- .exit = i915_pmu_exit },
>>>> { .init = i915_pci_register_driver,
>>>> .exit = i915_pci_unregister_driver },
>>>> { .init = i915_perf_sysctl_register,
>>>>diff --git a/drivers/gpu/drm/i915/i915_pmu.c
>>>>b/drivers/gpu/drm/i915/i915_pmu.c
>>>>index e55db036be1bb..652964ef0643c 100644
>>>>--- a/drivers/gpu/drm/i915/i915_pmu.c
>>>>+++ b/drivers/gpu/drm/i915/i915_pmu.c
>>>>@@ -28,9 +28,6 @@
>>>> BIT(I915_SAMPLE_WAIT) | \
>>>> BIT(I915_SAMPLE_SEMA))
>>>>
>>>>-static cpumask_t i915_pmu_cpumask;
>>>>-static unsigned int i915_pmu_target_cpu = -1;
>>>>-
>>>> static struct i915_pmu *event_to_pmu(struct perf_event *event)
>>>> {
>>>> return container_of(event->pmu, struct i915_pmu, base);
>>>>@@ -642,10 +639,6 @@ static int i915_pmu_event_init(struct
>>>>perf_event *event)
>>>> if (event->cpu < 0)
>>>> return -EINVAL;
>>>>
>>>>- /* only allow running on one cpu at a time */
>>>>- if (!cpumask_test_cpu(event->cpu, &i915_pmu_cpumask))
>>>>- return -EINVAL;
>>>>-
>>>> if (is_engine_event(event))
>>>> ret = engine_event_init(event);
>>>> else
>>>>@@ -940,23 +933,6 @@ static ssize_t i915_pmu_event_show(struct
>>>>device *dev,
>>>> return sprintf(buf, "config=0x%lx\n", eattr->val);
>>>> }
>>>>
>>>>-static ssize_t cpumask_show(struct device *dev,
>>>>- struct device_attribute *attr, char *buf)
>>>>-{
>>>>- return cpumap_print_to_pagebuf(true, buf, &i915_pmu_cpumask);
>>>>-}
>>>>-
>>>>-static DEVICE_ATTR_RO(cpumask);
>>>>-
>>>>-static struct attribute *i915_cpumask_attrs[] = {
>>>>- &dev_attr_cpumask.attr,
>>>>- NULL,
>>>>-};
>>>>-
>>>>-static const struct attribute_group i915_pmu_cpumask_attr_group = {
>>>>- .attrs = i915_cpumask_attrs,
>>>>-};
>>>>-
>>>> #define __event(__counter, __name, __unit) \
>>>> { \
>>>> .counter = (__counter), \
>>>>@@ -1173,92 +1149,12 @@ static void free_event_attributes(struct
>>>>i915_pmu *pmu)
>>>> pmu->pmu_attr = NULL;
>>>> }
>>>>
>>>>-static int i915_pmu_cpu_online(unsigned int cpu, struct
>>>>hlist_node *node)
>>>>-{
>>>>- struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu),
>>>>cpuhp.node);
>>>>-
>>>>- /* Select the first online CPU as a designated reader. */
>>>>- if (cpumask_empty(&i915_pmu_cpumask))
>>>>- cpumask_set_cpu(cpu, &i915_pmu_cpumask);
>>>>-
>>>>- return 0;
>>>>-}
>>>>-
>>>>-static int i915_pmu_cpu_offline(unsigned int cpu, struct
>>>>hlist_node *node)
>>>>-{
>>>>- struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu),
>>>>cpuhp.node);
>>>>- unsigned int target = i915_pmu_target_cpu;
>>>>-
>>>>- /*
>>>>- * Unregistering an instance generates a CPU offline event
>>>>which we must
>>>>- * ignore to avoid incorrectly modifying the shared
>>>>i915_pmu_cpumask.
>>>>- */
>>>>- if (!pmu->registered)
>>>>- return 0;
>>>>-
>>>>- if (cpumask_test_and_clear_cpu(cpu, &i915_pmu_cpumask)) {
>>>>- target = cpumask_any_but(topology_sibling_cpumask(cpu), cpu);
>>>>-
>>>
>>>I'm not familar with the i915 PMU, but it seems suggest a core scope
>>>PMU, not a system-wide scope.
>>
>>counter is in a complete separate device - it doesn't depend on core or
>>die or pkg - not sure why it cared about topology_sibling_cpumask here.
>>
>>Also, in my tests it always chose cpu0 that is the boot cpu and can't be
>>offlined. Looking at our CI it seems this entire code is not tested at
>>all: the only test that in theory would exercise this just skips since
>>cpu0 can't go offline - https://intel-gfx-ci.01.org/tree/drm-tip/shards-all.html?testfilter=hotplug
>
>s/not tested at all/not currently tested/
>
>commit e59e74dc48a309cb848ffc3d76a0d61aa6803c05
>Author: Thomas Gleixner <tglx at linutronix.de>
>Date: Fri May 12 23:07:04 2023 +0200
>
> x86/topology: Remove CPU0 hotplug option
>
>So test worked for ~6 years and then transitioned to skip. :shrug:
right, indeed looking at the CI repo I see it there:
$ git grep CONFIG_BOOTPARAM_HOTPLUG_CPU0
kconfig/debug:CONFIG_BOOTPARAM_HOTPLUG_CPU0=y
kconfig/debug-kasan:CONFIG_BOOTPARAM_HOTPLUG_CPU0=y
$ git log --oneline -G CONFIG_BOOTPARAM_HOTPLUG_CPU0 kconfig/debug
3553bf4 kconfig: Dump current kconfigs used by CI
I sent this to igt yesterday:
https://patchwork.freedesktop.org/patch/633357/?series=143874&rev=1
I will reword that commit message to note that it was actually tested
before that kernel commit. The test worked because it only tried to toggle the
cpu0 and thus a migration succeeded to a sibling cpu, right?
For the kernel commit message I can add a comment about the counter
being indeed a system one and the use of topology_sibling_cpumask()
being wrong here. With that, can you review this patch?
thanks
Lucas De Marchi
>
>Regards,
>
>Tvrtko
>
>>>
>>>>- /* Migrate events if there is a valid target */
>>>>- if (target < nr_cpu_ids) {
>>>>- cpumask_set_cpu(target, &i915_pmu_cpumask);
>>>>- i915_pmu_target_cpu = target;
>>>>- }
>>>>- }
>>>>-
>>>>- if (target < nr_cpu_ids && target != pmu->cpuhp.cpu) {
>>>>- perf_pmu_migrate_context(&pmu->base, cpu, target);
>>>>- pmu->cpuhp.cpu = target;
>>>>- }
>>>>-
>>>>- return 0;
>>>>-}
>>>>-
>>>>-static enum cpuhp_state cpuhp_state = CPUHP_INVALID;
>>>>-
>>>>-int i915_pmu_init(void)
>>>>-{
>>>>- int ret;
>>>>-
>>>>- ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
>>>>- "perf/x86/intel/i915:online",
>>>>- i915_pmu_cpu_online,
>>>>- i915_pmu_cpu_offline);
>>>>- if (ret < 0)
>>>>- pr_notice("Failed to setup cpuhp state for i915 PMU! (%d)\n",
>>>>- ret);
>>>>- else
>>>>- cpuhp_state = ret;
>>>>-
>>>>- return 0;
>>>>-}
>>>>-
>>>>-void i915_pmu_exit(void)
>>>>-{
>>>>- if (cpuhp_state != CPUHP_INVALID)
>>>>- cpuhp_remove_multi_state(cpuhp_state);
>>>>-}
>>>>-
>>>>-static int i915_pmu_register_cpuhp_state(struct i915_pmu *pmu)
>>>>-{
>>>>- if (cpuhp_state == CPUHP_INVALID)
>>>>- return -EINVAL;
>>>>-
>>>>- return cpuhp_state_add_instance(cpuhp_state, &pmu->cpuhp.node);
>>>>-}
>>>>-
>>>>-static void i915_pmu_unregister_cpuhp_state(struct i915_pmu *pmu)
>>>>-{
>>>>- cpuhp_state_remove_instance(cpuhp_state, &pmu->cpuhp.node);
>>>>-}
>>>>-
>>>> void i915_pmu_register(struct drm_i915_private *i915)
>>>> {
>>>> struct i915_pmu *pmu = &i915->pmu;
>>>> const struct attribute_group *attr_groups[] = {
>>>> &i915_pmu_format_attr_group,
>>>> &pmu->events_attr_group,
>>>>- &i915_pmu_cpumask_attr_group,
>>>> NULL
>>>> };
>>>> int ret = -ENOMEM;
>>>>@@ -1266,7 +1162,6 @@ void i915_pmu_register(struct
>>>>drm_i915_private *i915)
>>>> spin_lock_init(&pmu->lock);
>>>> hrtimer_init(&pmu->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>>>> pmu->timer.function = i915_sample;
>>>>- pmu->cpuhp.cpu = -1;
>>>> init_rc6(pmu);
>>>>
>>>> if (IS_DGFX(i915)) {
>>>>@@ -1295,6 +1190,7 @@ void i915_pmu_register(struct
>>>>drm_i915_private *i915)
>>>>
>>>> pmu->base.module = THIS_MODULE;
>>>> pmu->base.task_ctx_nr = perf_invalid_context;
>>>>+ pmu->base.scope = PERF_PMU_SCOPE_SYS_WIDE;
>>>> pmu->base.event_init = i915_pmu_event_init;
>>>> pmu->base.add = i915_pmu_event_add;
>>>> pmu->base.del = i915_pmu_event_del;
>>>>@@ -1307,16 +1203,10 @@ void i915_pmu_register(struct
>>>>drm_i915_private *i915)
>>>> if (ret)
>>>> goto err_groups;
>>>>
>>>>- ret = i915_pmu_register_cpuhp_state(pmu);
>>>>- if (ret)
>>>>- goto err_unreg;
>>>>-
>>>> pmu->registered = true;
>>>>
>>>> return;
>>>>
>>>>-err_unreg:
>>>>- perf_pmu_unregister(&pmu->base);
>>>> err_groups:
>>>> kfree(pmu->base.attr_groups);
>>>> err_attr:
>>>>@@ -1340,8 +1230,6 @@ void i915_pmu_unregister(struct
>>>>drm_i915_private *i915)
>>>>
>>>> hrtimer_cancel(&pmu->timer);
>>>>
>>>>- i915_pmu_unregister_cpuhp_state(pmu);
>>>>-
>>>> perf_pmu_unregister(&pmu->base);
>>>> kfree(pmu->base.attr_groups);
>>>> if (IS_DGFX(i915))
>>>>diff --git a/drivers/gpu/drm/i915/i915_pmu.h
>>>>b/drivers/gpu/drm/i915/i915_pmu.h
>>>>index 8e66d63d0c9f9..53bce3d8bfbaf 100644
>>>>--- a/drivers/gpu/drm/i915/i915_pmu.h
>>>>+++ b/drivers/gpu/drm/i915/i915_pmu.h
>>>>@@ -56,13 +56,6 @@ struct i915_pmu_sample {
>>>> };
>>>>
>>>> struct i915_pmu {
>>>>- /**
>>>>- * @cpuhp: Struct used for CPU hotplug handling.
>>>>- */
>>>>- struct {
>>>>- struct hlist_node node;
>>>>- unsigned int cpu;
>>>>- } cpuhp;
>>>> /**
>>>> * @base: PMU base.
>>>> */
>>>>@@ -155,15 +148,11 @@ struct i915_pmu {
>>>> };
>>>>
>>>> #ifdef CONFIG_PERF_EVENTS
>>>>-int i915_pmu_init(void);
>>>>-void i915_pmu_exit(void);
>>>> void i915_pmu_register(struct drm_i915_private *i915);
>>>> void i915_pmu_unregister(struct drm_i915_private *i915);
>>>> void i915_pmu_gt_parked(struct intel_gt *gt);
>>>> void i915_pmu_gt_unparked(struct intel_gt *gt);
>>>> #else
>>>>-static inline int i915_pmu_init(void) { return 0; }
>>>>-static inline void i915_pmu_exit(void) {}
>>>> static inline void i915_pmu_register(struct drm_i915_private *i915) {}
>>>> static inline void i915_pmu_unregister(struct drm_i915_private
>>>>*i915) {}
>>>> static inline void i915_pmu_gt_parked(struct intel_gt *gt) {}
>>>
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