Commit 429b7638 authored by Besar Wicaksono's avatar Besar Wicaksono Committed by Will Deacon
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perf: add NVIDIA Tegra410 CPU Memory Latency PMU 



Adds CPU Memory (CMEM) Latency PMU support in Tegra410 SOC.
The PMU is used to measure latency between the edge of the
Unified Coherence Fabric to the local system DRAM.

Reviewed-by: default avatarIlkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: default avatarBesar Wicaksono <bwicaksono@nvidia.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 3dd73022

Documentation/admin-guide/perf/nvidia-tegra410-pmu.rst

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@@ -8,6 +8,7 @@ metrics like memory bandwidth, latency, and utilization: 
* Unified Coherence Fabric (UCF)

* PCIE

* PCIE-TGT

* CPU Memory (CMEM) Latency



PMU Driver

----------
@@ -344,3 +345,27 @@ Example usage: 
  0x10000 to 0x100FF on socket 0's PCIE RC-1::



    perf stat -a -e nvidia_pcie_tgt_pmu_0_rc_1/event=0x1,dst_addr_base=0x10000,dst_addr_mask=0xFFF00,dst_addr_en=0x1/



CPU Memory (CMEM) Latency PMU

-----------------------------



This PMU monitors latency events of memory read requests from the edge of the

Unified Coherence Fabric (UCF) to local CPU DRAM:



  * RD_REQ counters: count read requests (32B per request).

  * RD_CUM_OUTS counters: accumulated outstanding request counter, which track

    how many cycles the read requests are in flight.

  * CYCLES counter: counts the number of elapsed cycles.



The average latency is calculated as::



   FREQ_IN_GHZ = CYCLES / ELAPSED_TIME_IN_NS

   AVG_LATENCY_IN_CYCLES = RD_CUM_OUTS / RD_REQ

   AVERAGE_LATENCY_IN_NS = AVG_LATENCY_IN_CYCLES / FREQ_IN_GHZ



The events and configuration options of this PMU device are described in sysfs,

see /sys/bus/event_source/devices/nvidia_cmem_latency_pmu_<socket-id>.



Example usage::



  perf stat -a -e '{nvidia_cmem_latency_pmu_0/rd_req/,nvidia_cmem_latency_pmu_0/rd_cum_outs/,nvidia_cmem_latency_pmu_0/cycles/}'

drivers/perf/Kconfig

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@@ -311,4 +311,11 @@ config MARVELL_PEM_PMU 
	  Enable support for PCIe Interface performance monitoring

	  on Marvell platform.



config NVIDIA_TEGRA410_CMEM_LATENCY_PMU

	tristate "NVIDIA Tegra410 CPU Memory Latency PMU"

	depends on ARM64 && ACPI

	help

	  Enable perf support for CPU memory latency counters monitoring on

	  NVIDIA Tegra410 SoC.



endmenu

drivers/perf/Makefile

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@@ -35,3 +35,4 @@ obj-$(CONFIG_DWC_PCIE_PMU) += dwc_pcie_pmu.o 
obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += arm_cspmu/

obj-$(CONFIG_MESON_DDR_PMU) += amlogic/

obj-$(CONFIG_CXL_PMU) += cxl_pmu.o

obj-$(CONFIG_NVIDIA_TEGRA410_CMEM_LATENCY_PMU) += nvidia_t410_cmem_latency_pmu.o

drivers/perf/nvidia_t410_cmem_latency_pmu.c

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