Amlogic SoC DDR Bandwidth Performance Monitoring Unit (PMU)ΒΆ

The Amlogic Meson G12 SoC contains a bandwidth monitor inside DRAM controller. The monitor includes 4 channels. Each channel can count the request accessing DRAM. The channel can count up to 3 AXI port simultaneously. It can be helpful to show if the performance bottleneck is on DDR bandwidth.

Currently, this driver supports the following 5 perf events:

  • meson_ddr_bw/total_rw_bytes/
  • meson_ddr_bw/chan_1_rw_bytes/
  • meson_ddr_bw/chan_2_rw_bytes/
  • meson_ddr_bw/chan_3_rw_bytes/
  • meson_ddr_bw/chan_4_rw_bytes/

meson_ddr_bw/chan_{1,2,3,4}_rw_bytes/ events are channel-specific events. Each channel support filtering, which can let the channel to monitor individual IP module in SoC.

Below are DDR access request event filter keywords:

  • arm - from CPU
  • vpu_read1 - from OSD + VPP read
  • gpu - from 3D GPU
  • pcie - from PCIe controller
  • hdcp - from HDCP controller
  • hevc_front - from HEVC codec front end
  • usb3_0 - from USB3.0 controller
  • hevc_back - from HEVC codec back end
  • h265enc - from HEVC encoder
  • vpu_read2 - from DI read
  • vpu_write1 - from VDIN write
  • vpu_write2 - from di write
  • vdec - from legacy codec video decoder
  • hcodec - from H264 encoder
  • ge2d - from ge2d
  • spicc1 - from SPI controller 1
  • usb0 - from USB2.0 controller 0
  • dma - from system DMA controller 1
  • arb0 - from arb0
  • sd_emmc_b - from SD eMMC b controller
  • usb1 - from USB2.0 controller 1
  • audio - from Audio module
  • sd_emmc_c - from SD eMMC c controller
  • spicc2 - from SPI controller 2
  • ethernet - from Ethernet controller

Examples:

  • Show the total DDR bandwidth per seconds:

    perf stat -a -e meson_ddr_bw/total_rw_bytes/ -I 1000 sleep 10

  • Show individual DDR bandwidth from CPU and GPU respectively, as well as sum of them:

    perf stat -a -e meson_ddr_bw/chan_1_rw_bytes,arm=1/ -I 1000 sleep 10
perf stat -a -e meson_ddr_bw/chan_2_rw_bytes,gpu=1/ -I 1000 sleep 10
perf stat -a -e meson_ddr_bw/chan_3_rw_bytes,arm=1,gpu=1/ -I 1000 sleep 10