.. SPDX-License-Identifier: GPL-2.0
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Amlogic SoC DDR Bandwidth Performance Monitoring Unit (PMU)
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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:
.. code-block:: bash
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:
.. code-block:: bash
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