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powerpc/perf: Add thread IMC PMU support
authorAnju T Sudhakar <anju@linux.vnet.ibm.com>
Tue, 18 Jul 2017 21:36:36 +0000 (03:06 +0530)
committerMichael Ellerman <mpe@ellerman.id.au>
Tue, 25 Jul 2017 12:55:46 +0000 (22:55 +1000)
Add support to register Thread In-Memory Collection PMU counters.
Patch adds thread IMC specific data structures, along with memory
init functions and CPU hotplug support.

Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/perf/imc-pmu.c
include/linux/cpuhotplug.h

index 482f8d6..46cd912 100644 (file)
@@ -37,6 +37,12 @@ static cpumask_t core_imc_cpumask;
 struct imc_pmu_ref *core_imc_refc;
 static struct imc_pmu *core_imc_pmu;
 
+/* Thread IMC data structures and variables */
+
+static DEFINE_PER_CPU(u64 *, thread_imc_mem);
+static struct imc_pmu *thread_imc_pmu;
+static int thread_imc_mem_size;
+
 struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
 {
        return container_of(event->pmu, struct imc_pmu, pmu);
@@ -728,15 +734,188 @@ static int core_imc_event_init(struct perf_event *event)
        return 0;
 }
 
-static u64 * get_event_base_addr(struct perf_event *event)
+/*
+ * Allocates a page of memory for each of the online cpus, and write the
+ * physical base address of that page to the LDBAR for that cpu.
+ *
+ * LDBAR Register Layout:
+ *
+ *  0          4         8         12        16        20        24        28
+ * | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - |
+ *   | |       [   ]    [                   Counter Address [8:50]
+ *   | * Mode    |
+ *   |           * PB Scope
+ *   * Enable/Disable
+ *
+ *  32        36        40        44        48        52        56        60
+ * | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - |
+ *           Counter Address [8:50]              ]
+ *
+ */
+static int thread_imc_mem_alloc(int cpu_id, int size)
+{
+       u64 ldbar_value, *local_mem = per_cpu(thread_imc_mem, cpu_id);
+       int phys_id = topology_physical_package_id(cpu_id);
+
+       if (!local_mem) {
+               /*
+                * This case could happen only once at start, since we dont
+                * free the memory in cpu offline path.
+                */
+               local_mem = page_address(alloc_pages_node(phys_id,
+                                 GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
+                                 get_order(size)));
+               if (!local_mem)
+                       return -ENOMEM;
+
+               per_cpu(thread_imc_mem, cpu_id) = local_mem;
+       }
+
+       ldbar_value = ((u64)local_mem & THREAD_IMC_LDBAR_MASK) | THREAD_IMC_ENABLE;
+
+       mtspr(SPRN_LDBAR, ldbar_value);
+       return 0;
+}
+
+static int ppc_thread_imc_cpu_online(unsigned int cpu)
 {
+       return thread_imc_mem_alloc(cpu, thread_imc_mem_size);
+}
+
+static int ppc_thread_imc_cpu_offline(unsigned int cpu)
+{
+       mtspr(SPRN_LDBAR, 0);
+       return 0;
+}
+
+static int thread_imc_cpu_init(void)
+{
+       return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
+                         "perf/powerpc/imc_thread:online",
+                         ppc_thread_imc_cpu_online,
+                         ppc_thread_imc_cpu_offline);
+}
+
+void thread_imc_pmu_sched_task(struct perf_event_context *ctx,
+                                     bool sched_in)
+{
+       int core_id;
+       struct imc_pmu_ref *ref;
+
+       if (!is_core_imc_mem_inited(smp_processor_id()))
+               return;
+
+       core_id = smp_processor_id() / threads_per_core;
        /*
-        * Subsequent patch will add code to detect caller imc pmu
-        * and return accordingly.
+        * imc pmus are enabled only when it is used.
+        * See if this is triggered for the first time.
+        * If yes, take the mutex lock and enable the counters.
+        * If not, just increment the count in ref count struct.
         */
+       ref = &core_imc_refc[core_id];
+       if (!ref)
+               return;
+
+       if (sched_in) {
+               mutex_lock(&ref->lock);
+               if (ref->refc == 0) {
+                       if (opal_imc_counters_start(OPAL_IMC_COUNTERS_CORE,
+                            get_hard_smp_processor_id(smp_processor_id()))) {
+                               mutex_unlock(&ref->lock);
+                               pr_err("thread-imc: Unable to start the counter\
+                                                       for core %d\n", core_id);
+                               return;
+                       }
+               }
+               ++ref->refc;
+               mutex_unlock(&ref->lock);
+       } else {
+               mutex_lock(&ref->lock);
+               ref->refc--;
+               if (ref->refc == 0) {
+                       if (opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
+                           get_hard_smp_processor_id(smp_processor_id()))) {
+                               mutex_unlock(&ref->lock);
+                               pr_err("thread-imc: Unable to stop the counters\
+                                                       for core %d\n", core_id);
+                               return;
+                       }
+               } else if (ref->refc < 0) {
+                       ref->refc = 0;
+               }
+               mutex_unlock(&ref->lock);
+       }
+
+       return;
+}
+
+static int thread_imc_event_init(struct perf_event *event)
+{
+       u32 config = event->attr.config;
+       struct task_struct *target;
+       struct imc_pmu *pmu;
+
+       if (event->attr.type != event->pmu->type)
+               return -ENOENT;
+
+       /* Sampling not supported */
+       if (event->hw.sample_period)
+               return -EINVAL;
+
+       event->hw.idx = -1;
+       pmu = imc_event_to_pmu(event);
+
+       /* Sanity check for config offset */
+       if (((config & IMC_EVENT_OFFSET_MASK) > pmu->counter_mem_size))
+               return -EINVAL;
+
+       target = event->hw.target;
+       if (!target)
+               return -EINVAL;
+
+       event->pmu->task_ctx_nr = perf_sw_context;
+       return 0;
+}
+
+static bool is_thread_imc_pmu(struct perf_event *event)
+{
+       if (!strncmp(event->pmu->name, "thread_imc", strlen("thread_imc")))
+               return true;
+
+       return false;
+}
+
+static u64 * get_event_base_addr(struct perf_event *event)
+{
+       u64 addr;
+
+       if (is_thread_imc_pmu(event)) {
+               addr = (u64)per_cpu(thread_imc_mem, smp_processor_id());
+               return (u64 *)(addr + (event->attr.config & IMC_EVENT_OFFSET_MASK));
+       }
+
        return (u64 *)event->hw.event_base;
 }
 
+static void thread_imc_pmu_start_txn(struct pmu *pmu,
+                                    unsigned int txn_flags)
+{
+       if (txn_flags & ~PERF_PMU_TXN_ADD)
+               return;
+       perf_pmu_disable(pmu);
+}
+
+static void thread_imc_pmu_cancel_txn(struct pmu *pmu)
+{
+       perf_pmu_enable(pmu);
+}
+
+static int thread_imc_pmu_commit_txn(struct pmu *pmu)
+{
+       perf_pmu_enable(pmu);
+       return 0;
+}
+
 static u64 imc_read_counter(struct perf_event *event)
 {
        u64 *addr, data;
@@ -794,6 +973,26 @@ static int imc_event_add(struct perf_event *event, int flags)
        return 0;
 }
 
+static int thread_imc_event_add(struct perf_event *event, int flags)
+{
+       if (flags & PERF_EF_START)
+               imc_event_start(event, flags);
+
+       /* Enable the sched_task to start the engine */
+       perf_sched_cb_inc(event->ctx->pmu);
+       return 0;
+}
+
+static void thread_imc_event_del(struct perf_event *event, int flags)
+{
+       /*
+        * Take a snapshot and calculate the delta and update
+        * the event counter values.
+        */
+       imc_event_update(event);
+       perf_sched_cb_dec(event->ctx->pmu);
+}
+
 /* update_pmu_ops : Populate the appropriate operations for "pmu" */
 static int update_pmu_ops(struct imc_pmu *pmu)
 {
@@ -815,6 +1014,15 @@ static int update_pmu_ops(struct imc_pmu *pmu)
                pmu->pmu.event_init = core_imc_event_init;
                pmu->attr_groups[IMC_CPUMASK_ATTR] = &imc_pmu_cpumask_attr_group;
                break;
+       case IMC_DOMAIN_THREAD:
+               pmu->pmu.event_init = thread_imc_event_init;
+               pmu->pmu.sched_task = thread_imc_pmu_sched_task;
+               pmu->pmu.add = thread_imc_event_add;
+               pmu->pmu.del = thread_imc_event_del;
+               pmu->pmu.start_txn = thread_imc_pmu_start_txn;
+               pmu->pmu.cancel_txn = thread_imc_pmu_cancel_txn;
+               pmu->pmu.commit_txn = thread_imc_pmu_commit_txn;
+               break;
        default:
                break;
        }
@@ -882,6 +1090,31 @@ static void cleanup_all_core_imc_memory(void)
        kfree(core_imc_refc);
 }
 
+static void thread_imc_ldbar_disable(void *dummy)
+{
+       /*
+        * By Zeroing LDBAR, we disable thread-imc
+        * updates.
+        */
+       mtspr(SPRN_LDBAR, 0);
+}
+
+void thread_imc_disable(void)
+{
+       on_each_cpu(thread_imc_ldbar_disable, NULL, 1);
+}
+
+static void cleanup_all_thread_imc_memory(void)
+{
+       int i, order = get_order(thread_imc_mem_size);
+
+       for_each_online_cpu(i) {
+               if (per_cpu(thread_imc_mem, i))
+                       free_pages((u64)per_cpu(thread_imc_mem, i), order);
+
+       }
+}
+
 /*
  * Common function to unregister cpu hotplug callback and
  * free the memory.
@@ -908,6 +1141,12 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
                cleanup_all_core_imc_memory();
        }
 
+       /* Free thread_imc memory */
+       if (pmu_ptr->domain == IMC_DOMAIN_THREAD) {
+               cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE);
+               cleanup_all_thread_imc_memory();
+       }
+
        /* Only free the attr_groups which are dynamically allocated  */
        kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]->attrs);
        kfree(pmu_ptr->attr_groups[IMC_EVENT_ATTR]);
@@ -923,7 +1162,7 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr, struct device_node *parent,
                                                                int pmu_index)
 {
        const char *s;
-       int nr_cores;
+       int nr_cores, cpu, res;
 
        if (of_property_read_string(parent, "name", &s))
                return -ENODEV;
@@ -959,6 +1198,21 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr, struct device_node *parent,
 
                core_imc_pmu = pmu_ptr;
                break;
+       case IMC_DOMAIN_THREAD:
+               /* Update the pmu name */
+               pmu_ptr->pmu.name = kasprintf(GFP_KERNEL, "%s%s", s, "_imc");
+               if (!pmu_ptr->pmu.name)
+                       return -ENOMEM;
+
+               thread_imc_mem_size = pmu_ptr->counter_mem_size;
+               for_each_online_cpu(cpu) {
+                       res = thread_imc_mem_alloc(cpu, pmu_ptr->counter_mem_size);
+                       if (res)
+                               return res;
+               }
+
+               thread_imc_pmu = pmu_ptr;
+               break;
        default:
                return -EINVAL;
        }
@@ -1017,6 +1271,14 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id
                }
 
                break;
+       case IMC_DOMAIN_THREAD:
+               ret = thread_imc_cpu_init();
+               if (ret) {
+                       cleanup_all_thread_imc_memory();
+                       return ret;
+               }
+
+               break;
        default:
                return  -1;     /* Unknown domain */
        }
index 1be505d..1bc7dcf 100644 (file)
@@ -141,6 +141,7 @@ enum cpuhp_state {
        CPUHP_AP_PERF_ARM_QCOM_L3_ONLINE,
        CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
        CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
+       CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
        CPUHP_AP_WORKQUEUE_ONLINE,
        CPUHP_AP_RCUTREE_ONLINE,
        CPUHP_AP_ONLINE_DYN,