95 lines · plain
1======================================================================2Synopsys DesignWare Cores (DWC) PCIe Performance Monitoring Unit (PMU)3======================================================================4 5DesignWare Cores (DWC) PCIe PMU6===============================7 8The PMU is a PCIe configuration space register block provided by each PCIe Root9Port in a Vendor-Specific Extended Capability named RAS D.E.S (Debug, Error10injection, and Statistics).11 12As the name indicates, the RAS DES capability supports system level13debugging, AER error injection, and collection of statistics. To facilitate14collection of statistics, Synopsys DesignWare Cores PCIe controller15provides the following two features:16 17- one 64-bit counter for Time Based Analysis (RX/TX data throughput and18 time spent in each low-power LTSSM state) and19- one 32-bit counter for Event Counting (error and non-error events for20 a specified lane)21 22Note: There is no interrupt for counter overflow.23 24Time Based Analysis25-------------------26 27Using this feature you can obtain information regarding RX/TX data28throughput and time spent in each low-power LTSSM state by the controller.29The PMU measures data in two categories:30 31- Group#0: Percentage of time the controller stays in LTSSM states.32- Group#1: Amount of data processed (Units of 16 bytes).33 34Lane Event counters35-------------------36 37Using this feature you can obtain Error and Non-Error information in38specific lane by the controller. The PMU event is selected by all of:39 40- Group i41- Event j within the Group i42- Lane k43 44Some of the events only exist for specific configurations.45 46DesignWare Cores (DWC) PCIe PMU Driver47=======================================48 49This driver adds PMU devices for each PCIe Root Port named based on the SBDF of50the Root Port. For example,51 52 0001:30:03.0 PCI bridge: Device 1ded:8000 (rev 01)53 54the PMU device name for this Root Port is dwc_rootport_13018.55 56The DWC PCIe PMU driver registers a perf PMU driver, which provides57description of available events and configuration options in sysfs, see58/sys/bus/event_source/devices/dwc_rootport_{sbdf}.59 60The "format" directory describes format of the config fields of the61perf_event_attr structure. The "events" directory provides configuration62templates for all documented events. For example,63"Rx_PCIe_TLP_Data_Payload" is an equivalent of "eventid=0x22,type=0x1".64 65The "perf list" command shall list the available events from sysfs, e.g.::66 67 $# perf list | grep dwc_rootport68 <...>69 dwc_rootport_13018/Rx_PCIe_TLP_Data_Payload/ [Kernel PMU event]70 <...>71 dwc_rootport_13018/rx_memory_read,lane=?/ [Kernel PMU event]72 73Time Based Analysis Event Usage74-------------------------------75 76Example usage of counting PCIe RX TLP data payload (Units of bytes)::77 78 $# perf stat -a -e dwc_rootport_13018/Rx_PCIe_TLP_Data_Payload/79 80The average RX/TX bandwidth can be calculated using the following formula:81 82 PCIe RX Bandwidth = Rx_PCIe_TLP_Data_Payload / Measure_Time_Window83 PCIe TX Bandwidth = Tx_PCIe_TLP_Data_Payload / Measure_Time_Window84 85Lane Event Usage86-------------------------------87 88Each lane has the same event set and to avoid generating a list of hundreds89of events, the user need to specify the lane ID explicitly, e.g.::90 91 $# perf stat -a -e dwc_rootport_13018/rx_memory_read,lane=4/92 93The driver does not support sampling, therefore "perf record" will not94work. Per-task (without "-a") perf sessions are not supported.95