| Message ID | 20210608115700.85933-3-kjain@linux.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add perf interface to expose nvdimm | expand |
On Tue, Jun 08, 2021 at 05:26:58PM +0530, Kajol Jain wrote: > +static int nvdimm_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node) > +{ > + struct nvdimm_pmu *nd_pmu; > + u32 target; > + int nodeid; > + const struct cpumask *cpumask; > + > + nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node); > + > + /* Clear it, incase given cpu is set in nd_pmu->arch_cpumask */ > + cpumask_test_and_clear_cpu(cpu, &nd_pmu->arch_cpumask); > + > + /* > + * If given cpu is not same as current designated cpu for > + * counter access, just return. > + */ > + if (cpu != nd_pmu->cpu) > + return 0; > + > + /* Check for any active cpu in nd_pmu->arch_cpumask */ > + target = cpumask_any(&nd_pmu->arch_cpumask); > + nd_pmu->cpu = target; > + > + /* > + * Incase we don't have any active cpu in nd_pmu->arch_cpumask, > + * check in given cpu's numa node list. > + */ > + if (target >= nr_cpu_ids) { > + nodeid = cpu_to_node(cpu); > + cpumask = cpumask_of_node(nodeid); > + target = cpumask_any_but(cpumask, cpu); > + nd_pmu->cpu = target; > + > + if (target >= nr_cpu_ids) > + return -1; > + } > + > + return 0; > +} > + > +static int nvdimm_pmu_cpu_online(unsigned int cpu, struct hlist_node *node) > +{ > + struct nvdimm_pmu *nd_pmu; > + > + nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node); > + > + if (nd_pmu->cpu >= nr_cpu_ids) > + nd_pmu->cpu = cpu; > + > + return 0; > +} > +static int nvdimm_pmu_cpu_hotplug_init(struct nvdimm_pmu *nd_pmu) > +{ > + int nodeid, rc; > + const struct cpumask *cpumask; > + > + /* > + * Incase cpu hotplug is not handled by arch specific code > + * they can still provide required cpumask which can be used > + * to get designatd cpu for counter access. > + * Check for any active cpu in nd_pmu->arch_cpumask. > + */ > + if (!cpumask_empty(&nd_pmu->arch_cpumask)) { > + nd_pmu->cpu = cpumask_any(&nd_pmu->arch_cpumask); > + } else { > + /* pick active cpu from the cpumask of device numa node. */ > + nodeid = dev_to_node(nd_pmu->dev); > + cpumask = cpumask_of_node(nodeid); > + nd_pmu->cpu = cpumask_any(cpumask); > + } > + > + rc = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "perf/nvdimm:online", > + nvdimm_pmu_cpu_online, nvdimm_pmu_cpu_offline); > + Did you actually test this hotplug stuff? That is, create a counter, unplug the CPU the counter was on, and continue counting? "perf stat -I" is a good option for this, concurrent with a hotplug. Because I don't think it's actually correct. The thing is perf core is strictly per-cpu, and it will place the event on a specific CPU context. If you then unplug that CPU, nothing will touch the events on that CPU anymore. What drivers that span CPUs need to do is call perf_pmu_migrate_context() whenever the CPU they were assigned to goes away. Please have a look at arch/x86/events/rapl.c or arch/x86/events/amd/power.c for relatively simple drivers that have this property.
On 6/8/21 11:06 PM, Peter Zijlstra wrote: > On Tue, Jun 08, 2021 at 05:26:58PM +0530, Kajol Jain wrote: >> +static int nvdimm_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node) >> +{ >> + struct nvdimm_pmu *nd_pmu; >> + u32 target; >> + int nodeid; >> + const struct cpumask *cpumask; >> + >> + nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node); >> + >> + /* Clear it, incase given cpu is set in nd_pmu->arch_cpumask */ >> + cpumask_test_and_clear_cpu(cpu, &nd_pmu->arch_cpumask); >> + >> + /* >> + * If given cpu is not same as current designated cpu for >> + * counter access, just return. >> + */ >> + if (cpu != nd_pmu->cpu) >> + return 0; >> + >> + /* Check for any active cpu in nd_pmu->arch_cpumask */ >> + target = cpumask_any(&nd_pmu->arch_cpumask); >> + nd_pmu->cpu = target; >> + >> + /* >> + * Incase we don't have any active cpu in nd_pmu->arch_cpumask, >> + * check in given cpu's numa node list. >> + */ >> + if (target >= nr_cpu_ids) { >> + nodeid = cpu_to_node(cpu); >> + cpumask = cpumask_of_node(nodeid); >> + target = cpumask_any_but(cpumask, cpu); >> + nd_pmu->cpu = target; >> + >> + if (target >= nr_cpu_ids) >> + return -1; >> + } >> + >> + return 0; >> +} >> + >> +static int nvdimm_pmu_cpu_online(unsigned int cpu, struct hlist_node *node) >> +{ >> + struct nvdimm_pmu *nd_pmu; >> + >> + nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node); >> + >> + if (nd_pmu->cpu >= nr_cpu_ids) >> + nd_pmu->cpu = cpu; >> + >> + return 0; >> +} > >> +static int nvdimm_pmu_cpu_hotplug_init(struct nvdimm_pmu *nd_pmu) >> +{ >> + int nodeid, rc; >> + const struct cpumask *cpumask; >> + >> + /* >> + * Incase cpu hotplug is not handled by arch specific code >> + * they can still provide required cpumask which can be used >> + * to get designatd cpu for counter access. >> + * Check for any active cpu in nd_pmu->arch_cpumask. >> + */ >> + if (!cpumask_empty(&nd_pmu->arch_cpumask)) { >> + nd_pmu->cpu = cpumask_any(&nd_pmu->arch_cpumask); >> + } else { >> + /* pick active cpu from the cpumask of device numa node. */ >> + nodeid = dev_to_node(nd_pmu->dev); >> + cpumask = cpumask_of_node(nodeid); >> + nd_pmu->cpu = cpumask_any(cpumask); >> + } >> + >> + rc = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "perf/nvdimm:online", >> + nvdimm_pmu_cpu_online, nvdimm_pmu_cpu_offline); >> + > > Did you actually test this hotplug stuff? > > That is, create a counter, unplug the CPU the counter was on, and > continue counting? "perf stat -I" is a good option for this, concurrent > with a hotplug. > > Because I don't think it's actually correct. The thing is perf core is > strictly per-cpu, and it will place the event on a specific CPU context. > If you then unplug that CPU, nothing will touch the events on that CPU > anymore. > > What drivers that span CPUs need to do is call > perf_pmu_migrate_context() whenever the CPU they were assigned to goes > away. Please have a look at arch/x86/events/rapl.c or > arch/x86/events/amd/power.c for relatively simple drivers that have this > property. > Hi Peter, Primarily I tested off-lining multiple cpus and checking if cpumask file is updating as expected, followed with perf stat commands. But I missed the scenario where we are off-lining CPU while running perf stat. My bad, thanks for pointing it out. I will fix this issue and send new version of the patchset. Thanks, Kajol Jain >
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile index 29203f3d3069..25dba6095612 100644 --- a/drivers/nvdimm/Makefile +++ b/drivers/nvdimm/Makefile @@ -18,6 +18,7 @@ nd_e820-y := e820.o libnvdimm-y := core.o libnvdimm-y += bus.o libnvdimm-y += dimm_devs.o +libnvdimm-y += nd_perf.o libnvdimm-y += dimm.o libnvdimm-y += region_devs.o libnvdimm-y += region.o diff --git a/drivers/nvdimm/nd_perf.c b/drivers/nvdimm/nd_perf.c new file mode 100644 index 000000000000..5cc1f1c65972 --- /dev/null +++ b/drivers/nvdimm/nd_perf.c @@ -0,0 +1,230 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * nd_perf.c: NVDIMM Device Performance Monitoring Unit support + * + * Perf interface to expose nvdimm performance stats. + * + * Copyright (C) 2021 IBM Corporation + */ + +#define pr_fmt(fmt) "nvdimm_pmu: " fmt + +#include <linux/nd.h> + +static ssize_t nvdimm_pmu_cpumask_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct pmu *pmu = dev_get_drvdata(dev); + struct nvdimm_pmu *nd_pmu; + + nd_pmu = container_of(pmu, struct nvdimm_pmu, pmu); + + return cpumap_print_to_pagebuf(true, buf, cpumask_of(nd_pmu->cpu)); +} + +static int nvdimm_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node) +{ + struct nvdimm_pmu *nd_pmu; + u32 target; + int nodeid; + const struct cpumask *cpumask; + + nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node); + + /* Clear it, incase given cpu is set in nd_pmu->arch_cpumask */ + cpumask_test_and_clear_cpu(cpu, &nd_pmu->arch_cpumask); + + /* + * If given cpu is not same as current designated cpu for + * counter access, just return. + */ + if (cpu != nd_pmu->cpu) + return 0; + + /* Check for any active cpu in nd_pmu->arch_cpumask */ + target = cpumask_any(&nd_pmu->arch_cpumask); + nd_pmu->cpu = target; + + /* + * Incase we don't have any active cpu in nd_pmu->arch_cpumask, + * check in given cpu's numa node list. + */ + if (target >= nr_cpu_ids) { + nodeid = cpu_to_node(cpu); + cpumask = cpumask_of_node(nodeid); + target = cpumask_any_but(cpumask, cpu); + nd_pmu->cpu = target; + + if (target >= nr_cpu_ids) + return -1; + } + + return 0; +} + +static int nvdimm_pmu_cpu_online(unsigned int cpu, struct hlist_node *node) +{ + struct nvdimm_pmu *nd_pmu; + + nd_pmu = hlist_entry_safe(node, struct nvdimm_pmu, node); + + if (nd_pmu->cpu >= nr_cpu_ids) + nd_pmu->cpu = cpu; + + return 0; +} + +static int create_cpumask_attr_group(struct nvdimm_pmu *nd_pmu) +{ + struct perf_pmu_events_attr *attr; + struct attribute **attrs; + struct attribute_group *nvdimm_pmu_cpumask_group; + + attr = kzalloc(sizeof(*attr), GFP_KERNEL); + if (!attr) + return -ENOMEM; + + attrs = kzalloc(2 * sizeof(struct attribute *), GFP_KERNEL); + if (!attrs) { + kfree(attr); + return -ENOMEM; + } + + /* Allocate memory for cpumask attribute group */ + nvdimm_pmu_cpumask_group = kzalloc(sizeof(*nvdimm_pmu_cpumask_group), GFP_KERNEL); + if (!nvdimm_pmu_cpumask_group) { + kfree(attr); + kfree(attrs); + return -ENOMEM; + } + + sysfs_attr_init(&attr->attr.attr); + attr->attr.attr.name = "cpumask"; + attr->attr.attr.mode = 0444; + attr->attr.show = nvdimm_pmu_cpumask_show; + attrs[0] = &attr->attr.attr; + attrs[1] = NULL; + + nvdimm_pmu_cpumask_group->attrs = attrs; + nd_pmu->attr_groups[NVDIMM_PMU_CPUMASK_ATTR] = nvdimm_pmu_cpumask_group; + return 0; +} + +static int nvdimm_pmu_cpu_hotplug_init(struct nvdimm_pmu *nd_pmu) +{ + int nodeid, rc; + const struct cpumask *cpumask; + + /* + * Incase cpu hotplug is not handled by arch specific code + * they can still provide required cpumask which can be used + * to get designatd cpu for counter access. + * Check for any active cpu in nd_pmu->arch_cpumask. + */ + if (!cpumask_empty(&nd_pmu->arch_cpumask)) { + nd_pmu->cpu = cpumask_any(&nd_pmu->arch_cpumask); + } else { + /* pick active cpu from the cpumask of device numa node. */ + nodeid = dev_to_node(nd_pmu->dev); + cpumask = cpumask_of_node(nodeid); + nd_pmu->cpu = cpumask_any(cpumask); + } + + rc = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "perf/nvdimm:online", + nvdimm_pmu_cpu_online, nvdimm_pmu_cpu_offline); + + if (rc < 0) + return rc; + + nd_pmu->cpuhp_state = rc; + + /* Register the pmu instance for cpu hotplug */ + rc = cpuhp_state_add_instance_nocalls(nd_pmu->cpuhp_state, &nd_pmu->node); + if (rc) { + cpuhp_remove_multi_state(nd_pmu->cpuhp_state); + return rc; + } + + /* Create cpumask attribute group */ + rc = create_cpumask_attr_group(nd_pmu); + if (rc) { + cpuhp_state_remove_instance_nocalls(nd_pmu->cpuhp_state, &nd_pmu->node); + cpuhp_remove_multi_state(nd_pmu->cpuhp_state); + return rc; + } + + return 0; +} + +void nvdimm_pmu_free_hotplug_memory(struct nvdimm_pmu *nd_pmu) +{ + cpuhp_state_remove_instance_nocalls(nd_pmu->cpuhp_state, &nd_pmu->node); + cpuhp_remove_multi_state(nd_pmu->cpuhp_state); + + if (nd_pmu->attr_groups[NVDIMM_PMU_CPUMASK_ATTR]) + kfree(nd_pmu->attr_groups[NVDIMM_PMU_CPUMASK_ATTR]->attrs); + kfree(nd_pmu->attr_groups[NVDIMM_PMU_CPUMASK_ATTR]); +} + +int register_nvdimm_pmu(struct nvdimm_pmu *nd_pmu, struct platform_device *pdev) +{ + int rc; + + if (!nd_pmu || !pdev) + return -EINVAL; + + /* event functions like add/del/read/event_init should not be NULL */ + if (WARN_ON_ONCE(!(nd_pmu->event_init && nd_pmu->add && nd_pmu->del && nd_pmu->read))) + return -EINVAL; + + nd_pmu->pmu.task_ctx_nr = perf_invalid_context; + nd_pmu->pmu.name = nd_pmu->name; + nd_pmu->pmu.event_init = nd_pmu->event_init; + nd_pmu->pmu.add = nd_pmu->add; + nd_pmu->pmu.del = nd_pmu->del; + nd_pmu->pmu.read = nd_pmu->read; + + nd_pmu->pmu.attr_groups = nd_pmu->attr_groups; + nd_pmu->pmu.capabilities = PERF_PMU_CAP_NO_INTERRUPT | + PERF_PMU_CAP_NO_EXCLUDE; + + /* + * Add platform_device->dev pointer to nvdimm_pmu to access + * device data in events functions. + */ + nd_pmu->dev = &pdev->dev; + + /* + * Incase cpumask attribute is set it means cpu + * hotplug is handled by the arch specific code and + * we can skip calling hotplug_init. + */ + if (!nd_pmu->attr_groups[NVDIMM_PMU_CPUMASK_ATTR]) { + /* init cpuhotplug */ + rc = nvdimm_pmu_cpu_hotplug_init(nd_pmu); + if (rc) { + pr_info("cpu hotplug feature failed for device: %s\n", nd_pmu->name); + return rc; + } + } + + rc = perf_pmu_register(&nd_pmu->pmu, nd_pmu->name, -1); + if (rc) { + nvdimm_pmu_free_hotplug_memory(nd_pmu); + return rc; + } + + pr_info("%s NVDIMM performance monitor support registered\n", + nd_pmu->name); + + return 0; +} +EXPORT_SYMBOL_GPL(register_nvdimm_pmu); + +void unregister_nvdimm_pmu(struct nvdimm_pmu *nd_pmu) +{ + /* handle freeing of memory nd_pmu in arch specific code */ + perf_pmu_unregister(&nd_pmu->pmu); + nvdimm_pmu_free_hotplug_memory(nd_pmu); +} +EXPORT_SYMBOL_GPL(unregister_nvdimm_pmu); diff --git a/include/linux/nd.h b/include/linux/nd.h index 712499cf7335..7d8b4f7d277d 100644 --- a/include/linux/nd.h +++ b/include/linux/nd.h @@ -66,6 +66,9 @@ struct nvdimm_pmu { struct cpumask arch_cpumask; }; +int register_nvdimm_pmu(struct nvdimm_pmu *nvdimm, struct platform_device *pdev); +void unregister_nvdimm_pmu(struct nvdimm_pmu *nd_pmu); + struct nd_device_driver { struct device_driver drv; unsigned long type;
A common interface is added to get performance stats reporting support for nvdimm devices. Added interface includes support for pmu register/unregister functions, cpu hotplug and pmu event functions like event_init/add/read/del. User could use the standard perf tool to access perf events exposed via pmu. Signed-off-by: Kajol Jain <kjain@linux.ibm.com> --- drivers/nvdimm/Makefile | 1 + drivers/nvdimm/nd_perf.c | 230 +++++++++++++++++++++++++++++++++++++++ include/linux/nd.h | 3 + 3 files changed, 234 insertions(+) create mode 100644 drivers/nvdimm/nd_perf.c