Messages in this thread Patch in this message | | | Date | Fri, 11 Nov 2016 11:30:29 +0100 | From | Jan Glauber <> | Subject | Re: [PATCH v4 1/5] arm64: perf: Basic uncore counter support for Cavium ThunderX SOC |
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Hi Will,
thanks for the review!
On Tue, Nov 08, 2016 at 11:50:10PM +0000, Will Deacon wrote: > Hi Jan, > > Thanks for posting an updated series. I have a few minor comments, which > we can hopefully address in time for 4.10. > > Also, have you run the perf fuzzer with this series applied?
No, that's new to me. Will try it.
> https://github.com/deater/perf_event_tests > > (build the tests and look under the fuzzer/ directory for the tool) > > On Sat, Oct 29, 2016 at 01:55:29PM +0200, Jan Glauber wrote: > > Provide "uncore" facilities for different non-CPU performance > > counter units. > > > > The uncore PMUs can be found under /sys/bus/event_source/devices. > > All counters are exported via sysfs in the corresponding events > > files under the PMU directory so the perf tool can list the event names. > > > > There are some points that are special in this implementation: > > > > 1) The PMU detection relies on PCI device detection. If a > > matching PCI device is found the PMU is created. The code can deal > > with multiple units of the same type, e.g. more than one memory > > controller. > > > > 2) Counters are summarized across different units of the same type > > on one NUMA node but not across NUMA nodes. > > For instance L2C TAD 0..7 are presented as a single counter > > (adding the values from TAD 0 to 7). Although losing the ability > > to read a single value the merged values are easier to use. > > > > 3) The counters are not CPU related. A random CPU is picked regardless > > of the NUMA node. There is a small performance penalty for accessing > > counters on a remote note but reading a performance counter is a > > slow operation anyway. > > > > Signed-off-by: Jan Glauber <jglauber@cavium.com> > > --- > > drivers/perf/Kconfig | 13 ++ > > drivers/perf/Makefile | 1 + > > drivers/perf/uncore/Makefile | 1 + > > drivers/perf/uncore/uncore_cavium.c | 351 ++++++++++++++++++++++++++++++++++++ > > drivers/perf/uncore/uncore_cavium.h | 71 ++++++++ > > We already have "uncore" PMUs under drivers/perf, so I'd prefer that we > renamed this a bit to reflect better what's going on. How about: > > drivers/perf/cavium/ > > and then > > drivers/perf/cavium/uncore_thunder.[ch] > > ?
OK, agreed.
> > include/linux/cpuhotplug.h | 1 + > > 6 files changed, 438 insertions(+) > > create mode 100644 drivers/perf/uncore/Makefile > > create mode 100644 drivers/perf/uncore/uncore_cavium.c > > create mode 100644 drivers/perf/uncore/uncore_cavium.h > > > > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig > > index 4d5c5f9..3266c87 100644 > > --- a/drivers/perf/Kconfig > > +++ b/drivers/perf/Kconfig > > @@ -19,4 +19,17 @@ config XGENE_PMU > > help > > Say y if you want to use APM X-Gene SoC performance monitors. > > > > +config UNCORE_PMU > > + bool > > This isn't needed.
I thought about a symbol for all uncore pmus. But when drivers/perf is already that it can be removed.
> > + > > +config UNCORE_PMU_CAVIUM > > + depends on PERF_EVENTS && NUMA && ARM64 > > + bool "Cavium uncore PMU support" > > Please mentioned Thunder somewhere, since that's the SoC being supported.
OK.
> > + select UNCORE_PMU > > + default y > > + help > > + Say y if you want to access performance counters of subsystems > > + on a Cavium SOC like cache controller, memory controller or > > + processor interconnect. > > + > > endmenu > > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile > > index b116e98..d6c02c9 100644 > > --- a/drivers/perf/Makefile > > +++ b/drivers/perf/Makefile > > @@ -1,2 +1,3 @@ > > obj-$(CONFIG_ARM_PMU) += arm_pmu.o > > obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o > > +obj-y += uncore/ > > diff --git a/drivers/perf/uncore/Makefile b/drivers/perf/uncore/Makefile > > new file mode 100644 > > index 0000000..6130e18 > > --- /dev/null > > +++ b/drivers/perf/uncore/Makefile > > @@ -0,0 +1 @@ > > +obj-$(CONFIG_UNCORE_PMU_CAVIUM) += uncore_cavium.o > > diff --git a/drivers/perf/uncore/uncore_cavium.c b/drivers/perf/uncore/uncore_cavium.c > > new file mode 100644 > > index 0000000..a7b4277 > > --- /dev/null > > +++ b/drivers/perf/uncore/uncore_cavium.c > > @@ -0,0 +1,351 @@ > > +/* > > + * Cavium Thunder uncore PMU support. > > + * > > + * Copyright (C) 2015,2016 Cavium Inc. > > + * Author: Jan Glauber <jan.glauber@cavium.com> > > + */ > > + > > +#include <linux/cpufeature.h> > > +#include <linux/numa.h> > > +#include <linux/slab.h> > > + > > +#include "uncore_cavium.h" > > + > > +/* > > + * Some notes about the various counters supported by this "uncore" PMU > > + * and the design: > > + * > > + * All counters are 64 bit long. > > + * There are no overflow interrupts. > > + * Counters are summarized per node/socket. > > + * Most devices appear as separate PCI devices per socket with the exception > > + * of OCX TLK which appears as one PCI device per socket and contains several > > + * units with counters that are merged. > > + * Some counters are selected via a control register (L2C TAD) and read by > > + * a number of counter registers, others (L2C CBC, LMC & OCX TLK) have > > + * one dedicated counter per event. > > + * Some counters are not stoppable (L2C CBC & LMC). > > + * Some counters are read-only (LMC). > > + * All counters belong to PCI devices, the devices may have additional > > + * drivers but we assume we are the only user of the counter registers. > > + * We map the whole PCI BAR so we must be careful to forbid access to > > + * addresses that contain neither counters nor counter control registers. > > + */ > > + > > +void thunder_uncore_read(struct perf_event *event) > > +{ > Rather than have a bunch of global symbols that are called from the > individual drivers, why don't you pass a struct of function pointers to > their respective init functions and keep the internals private?
Most of these functions are already in struct pmu. What I can do is set the shared functions in thunder_uncore_setup as default, and only override them as needed (like thunder_uncore_read_ocx_tlk) or the other way around (use default if not set already). Then I can get rid of them.
> > + struct thunder_uncore *uncore = to_uncore(event->pmu); > > + struct hw_perf_event *hwc = &event->hw; > > + struct thunder_uncore_node *node; > > + struct thunder_uncore_unit *unit; > > + u64 prev, delta, new = 0; > > + > > + node = get_node(hwc->config, uncore); > > + > > + /* read counter values from all units on the node */ > > + list_for_each_entry(unit, &node->unit_list, entry) > > + new += readq(hwc->event_base + unit->map); > > + > > + prev = local64_read(&hwc->prev_count); > > + local64_set(&hwc->prev_count, new); > > + delta = new - prev; > > + local64_add(delta, &event->count); > > +} > > + > > +int thunder_uncore_add(struct perf_event *event, int flags, u64 config_base, > > + u64 event_base) > > +{ > > + struct thunder_uncore *uncore = to_uncore(event->pmu); > > + struct hw_perf_event *hwc = &event->hw; > > + struct thunder_uncore_node *node; > > + int id; > > + > > + node = get_node(hwc->config, uncore); > > + id = get_id(hwc->config); > > + > > + if (!cmpxchg(&node->events[id], NULL, event)) > > + hwc->idx = id; > > Does this need to be a full-fat cmpxchg? Who are you racing with?
Just copy'n'paste from the existing drivers. I guess it can be relaxed.
> > + > > + if (hwc->idx == -1) > > + return -EBUSY; > > This would be much clearer as an else statement after the cmpxchg.
Agreed.
> > + > > + hwc->config_base = config_base; > > + hwc->event_base = event_base; > > + hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED; > > + > > + if (flags & PERF_EF_START) > > + uncore->pmu.start(event, PERF_EF_RELOAD); > > + > > + return 0; > > +} > > + > > +void thunder_uncore_del(struct perf_event *event, int flags) > > +{ > > + struct thunder_uncore *uncore = to_uncore(event->pmu); > > + struct hw_perf_event *hwc = &event->hw; > > + struct thunder_uncore_node *node; > > + int i; > > + > > + event->pmu->stop(event, PERF_EF_UPDATE); > > + > > + /* > > + * For programmable counters we need to check where we installed it. > > + * To keep this function generic always test the more complicated > > + * case (free running counters won't need the loop). > > + */ > > + node = get_node(hwc->config, uncore); > > + for (i = 0; i < node->num_counters; i++) { > > + if (cmpxchg(&node->events[i], event, NULL) == event) > > + break; > > + } > > + hwc->idx = -1; > > +} > > + > > +void thunder_uncore_start(struct perf_event *event, int flags) > > +{ > > + struct thunder_uncore *uncore = to_uncore(event->pmu); > > + struct hw_perf_event *hwc = &event->hw; > > + struct thunder_uncore_node *node; > > + struct thunder_uncore_unit *unit; > > + u64 new = 0; > > + > > + /* read counter values from all units on the node */ > > + node = get_node(hwc->config, uncore); > > + list_for_each_entry(unit, &node->unit_list, entry) > > + new += readq(hwc->event_base + unit->map); > > + local64_set(&hwc->prev_count, new); > > + > > + hwc->state = 0; > > + perf_event_update_userpage(event); > > +} > > + > > +void thunder_uncore_stop(struct perf_event *event, int flags) > > +{ > > + struct hw_perf_event *hwc = &event->hw; > > + > > + hwc->state |= PERF_HES_STOPPED; > > + > > + if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) { > > + thunder_uncore_read(event); > > + hwc->state |= PERF_HES_UPTODATE; > > + } > > +} > > + > > +int thunder_uncore_event_init(struct perf_event *event) > > +{ > > + struct hw_perf_event *hwc = &event->hw; > > + struct thunder_uncore_node *node; > > + struct thunder_uncore *uncore; > > + > > + if (event->attr.type != event->pmu->type) > > + return -ENOENT; > > + > > + /* we do not support sampling */ > > + if (is_sampling_event(event)) > > + return -EINVAL; > > + > > + /* counters do not have these bits */ > > + if (event->attr.exclude_user || > > + event->attr.exclude_kernel || > > + event->attr.exclude_host || > > + event->attr.exclude_guest || > > + event->attr.exclude_hv || > > + event->attr.exclude_idle) > > + return -EINVAL; > > + > > + uncore = to_uncore(event->pmu); > > + if (!uncore) > > + return -ENODEV; > > + if (!uncore->event_valid(event->attr.config & UNCORE_EVENT_ID_MASK)) > > + return -EINVAL; > > + > > + /* check NUMA node */ > > + node = get_node(event->attr.config, uncore); > > + if (!node) { > > + pr_debug("Invalid NUMA node selected\n"); > > + return -EINVAL; > > + } > > + > > + hwc->config = event->attr.config; > > + hwc->idx = -1; > > + return 0; > > +} > > + > > +static ssize_t thunder_uncore_attr_show_cpumask(struct device *dev, > > + struct device_attribute *attr, > > + char *buf) > > +{ > > + struct pmu *pmu = dev_get_drvdata(dev); > > + struct thunder_uncore *uncore = > > + container_of(pmu, struct thunder_uncore, pmu); > > + > > + return cpumap_print_to_pagebuf(true, buf, &uncore->active_mask); > > +} > > +static DEVICE_ATTR(cpumask, S_IRUGO, thunder_uncore_attr_show_cpumask, NULL); > > + > > +static struct attribute *thunder_uncore_attrs[] = { > > + &dev_attr_cpumask.attr, > > + NULL, > > +}; > > + > > +struct attribute_group thunder_uncore_attr_group = { > > + .attrs = thunder_uncore_attrs, > > +}; > > + > > +ssize_t thunder_events_sysfs_show(struct device *dev, > > + struct device_attribute *attr, > > + char *page) > > +{ > > + struct perf_pmu_events_attr *pmu_attr = > > + container_of(attr, struct perf_pmu_events_attr, attr); > > + > > + if (pmu_attr->event_str) > > + return sprintf(page, "%s", pmu_attr->event_str); > > + > > + return 0; > > +} > > + > > +/* node attribute depending on number of NUMA nodes */ > > +static ssize_t node_show(struct device *dev, struct device_attribute *attr, > > + char *page) > > +{ > > + if (NODES_SHIFT) > > + return sprintf(page, "config:16-%d\n", 16 + NODES_SHIFT - 1); > > If NODES_SHIFT is 1, you'll end up with "config:16-16", which might confuse > userspace.
So should I use "config:16" in that case? Is it OK to use this also for NODES_SHIFT=0 ?
> > + else > > + return sprintf(page, "config:16\n"); > > +} > > + > > +struct device_attribute format_attr_node = __ATTR_RO(node); > > + > > +/* > > + * Thunder uncore events are independent from CPUs. Provide a cpumask > > + * nevertheless to prevent perf from adding the event per-cpu and just > > + * set the mask to one online CPU. Use the same cpumask for all uncore > > + * devices. > > + * > > + * There is a performance penalty for accessing a device from a CPU on > > + * another socket, but we do not care (yet). > > + */ > > +static int thunder_uncore_offline_cpu(unsigned int old_cpu, struct hlist_node *node) > > +{ > > + struct thunder_uncore *uncore = hlist_entry_safe(node, struct thunder_uncore, node); > > Why _safe?
Not required, will remove.
> > + int new_cpu; > > + > > + if (!cpumask_test_and_clear_cpu(old_cpu, &uncore->active_mask)) > > + return 0; > > + new_cpu = cpumask_any_but(cpu_online_mask, old_cpu); > > + if (new_cpu >= nr_cpu_ids) > > + return 0; > > + perf_pmu_migrate_context(&uncore->pmu, old_cpu, new_cpu); > > + cpumask_set_cpu(new_cpu, &uncore->active_mask); > > + return 0; > > +} > > + > > +static struct thunder_uncore_node * __init alloc_node(struct thunder_uncore *uncore, > > + int node_id, int counters) > > +{ > > + struct thunder_uncore_node *node; > > + > > + node = kzalloc(sizeof(*node), GFP_KERNEL); > > + if (!node) > > + return NULL; > > + node->num_counters = counters; > > + INIT_LIST_HEAD(&node->unit_list); > > + return node; > > +} > > + > > +int __init thunder_uncore_setup(struct thunder_uncore *uncore, int device_id, > > + struct pmu *pmu, int counters) > > +{ > > + unsigned int vendor_id = PCI_VENDOR_ID_CAVIUM; > > + struct thunder_uncore_unit *unit, *tmp; > > + struct thunder_uncore_node *node; > > + struct pci_dev *pdev = NULL; > > + int ret, node_id, found = 0; > > + > > + /* detect PCI devices */ > > + while ((pdev = pci_get_device(vendor_id, device_id, pdev))) { > > Redundant brackets?
OK
> > + if (!pdev) > > + break; > > Redundant check?
OK
> > + node_id = dev_to_node(&pdev->dev); > > + > > + /* allocate node if necessary */ > > + if (!uncore->nodes[node_id]) > > + uncore->nodes[node_id] = alloc_node(uncore, node_id, counters); > > + > > + node = uncore->nodes[node_id]; > > + if (!node) { > > + ret = -ENOMEM; > > + goto fail; > > + } > > + > > + unit = kzalloc(sizeof(*unit), GFP_KERNEL); > > + if (!unit) { > > + ret = -ENOMEM; > > + goto fail; > > + } > > + > > + unit->pdev = pdev; > > + unit->map = ioremap(pci_resource_start(pdev, 0), > > + pci_resource_len(pdev, 0)); > > + list_add(&unit->entry, &node->unit_list); > > + node->nr_units++; > > + found++; > > + } > > + > > + if (!found) > > + return -ENODEV; > > + > > + cpuhp_state_add_instance_nocalls(CPUHP_AP_UNCORE_CAVIUM_ONLINE, > > + &uncore->node); > > + > > + /* > > + * perf PMU is CPU dependent in difference to our uncore devices. > > + * Just pick a CPU and migrate away if it goes offline. > > + */ > > + cpumask_set_cpu(smp_processor_id(), &uncore->active_mask); > > + > > + uncore->pmu = *pmu; > > + ret = perf_pmu_register(&uncore->pmu, uncore->pmu.name, -1); > > + if (ret) > > + goto fail; > > + > > + return 0; > > + > > +fail: > > + node_id = 0; > > + while (uncore->nodes[node_id]) { > > + node = uncore->nodes[node_id]; > > + > > + list_for_each_entry_safe(unit, tmp, &node->unit_list, entry) { > > Why do you need the _safe variant?
OK, not needed
> Will
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