diff options
| -rw-r--r-- | include/linux/perf_event.h | 35 | ||||
| -rw-r--r-- | include/linux/sched.h | 2 | ||||
| -rw-r--r-- | kernel/events/core.c | 1 |
3 files changed, 38 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 3e270822b915..75d9b1e93f39 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1021,6 +1021,41 @@ struct perf_event_context { local_t nr_no_switch_fast; }; +/** + * struct perf_ctx_data - PMU specific data for a task + * @rcu_head: To avoid the race on free PMU specific data + * @refcount: To track users + * @global: To track system-wide users + * @ctx_cache: Kmem cache of PMU specific data + * @data: PMU specific data + * + * Currently, the struct is only used in Intel LBR call stack mode to + * save/restore the call stack of a task on context switches. + * + * The rcu_head is used to prevent the race on free the data. + * The data only be allocated when Intel LBR call stack mode is enabled. + * The data will be freed when the mode is disabled. + * The content of the data will only be accessed in context switch, which + * should be protected by rcu_read_lock(). + * + * Because of the alignment requirement of Intel Arch LBR, the Kmem cache + * is used to allocate the PMU specific data. The ctx_cache is to track + * the Kmem cache. + * + * Careful: Struct perf_ctx_data is added as a pointer in struct task_struct. + * When system-wide Intel LBR call stack mode is enabled, a buffer with + * constant size will be allocated for each task. + * Also, system memory consumption can further grow when the size of + * struct perf_ctx_data enlarges. + */ +struct perf_ctx_data { + struct rcu_head rcu_head; + refcount_t refcount; + int global; + struct kmem_cache *ctx_cache; + void *data; +}; + struct perf_cpu_pmu_context { struct perf_event_pmu_context epc; struct perf_event_pmu_context *task_epc; diff --git a/include/linux/sched.h b/include/linux/sched.h index 9632e3318e0d..7e183eeb50ec 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -65,6 +65,7 @@ struct mempolicy; struct nameidata; struct nsproxy; struct perf_event_context; +struct perf_ctx_data; struct pid_namespace; struct pipe_inode_info; struct rcu_node; @@ -1311,6 +1312,7 @@ struct task_struct { struct perf_event_context *perf_event_ctxp; struct mutex perf_event_mutex; struct list_head perf_event_list; + struct perf_ctx_data __rcu *perf_ctx_data; #endif #ifdef CONFIG_DEBUG_PREEMPT unsigned long preempt_disable_ip; diff --git a/kernel/events/core.c b/kernel/events/core.c index ace1bcc1e05f..20d28b7e30fb 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -14070,6 +14070,7 @@ int perf_event_init_task(struct task_struct *child, u64 clone_flags) child->perf_event_ctxp = NULL; mutex_init(&child->perf_event_mutex); INIT_LIST_HEAD(&child->perf_event_list); + child->perf_ctx_data = NULL; ret = perf_event_init_context(child, clone_flags); if (ret) { |