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The perf subsystem assumes that all counters are by default per-CPU. So the user space tool reads a counter from each CPU. However, the IOMMU counters are system-wide and can be read from any CPU. Here we use a CPU mask to restrict counting to one CPU to handle the issue. (with CPU hotplug notifier to choose a different CPU if the chosen one is taken off-line). The CPU is exposed to /sys/bus/event_source/devices/dmar*/cpumask for the user space perf tool. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Link: https://lore.kernel.org/r/20230128200428.1459118-6-kan.liang@linux.intel.com Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
1.6 KiB
1.6 KiB
What: /sys/bus/event_source/devices/dmar*/format Date: Jan 2023 KernelVersion: 6.3 Contact: Kan Liang kan.liang@linux.intel.com Description: Read-only. Attribute group to describe the magic bits that go into perf_event_attr.config, perf_event_attr.config1 or perf_event_attr.config2 for the IOMMU pmu. (See also ABI/testing/sysfs-bus-event_source-devices-format).
Each attribute in this group defines a bit range in
perf_event_attr.config, perf_event_attr.config1,
or perf_event_attr.config2. All supported attributes
are listed below (See the VT-d Spec 4.0 for possible
attribute values)::
event = "config:0-27" - event ID
event_group = "config:28-31" - event group ID
filter_requester_en = "config1:0" - Enable Requester ID filter
filter_domain_en = "config1:1" - Enable Domain ID filter
filter_pasid_en = "config1:2" - Enable PASID filter
filter_ats_en = "config1:3" - Enable Address Type filter
filter_page_table_en= "config1:4" - Enable Page Table Level filter
filter_requester_id = "config1:16-31" - Requester ID filter
filter_domain = "config1:32-47" - Domain ID filter
filter_pasid = "config2:0-21" - PASID filter
filter_ats = "config2:24-28" - Address Type filter
filter_page_table = "config2:32-36" - Page Table Level filter
What: /sys/bus/event_source/devices/dmar*/cpumask Date: Jan 2023 KernelVersion: 6.3 Contact: Kan Liang kan.liang@linux.intel.com Description: Read-only. This file always returns the CPU to which the IOMMU pmu is bound for access to all IOMMU pmu performance monitoring events.