[PATCH v9 2/4] docs/perf: Add documentation for the Amlogic G12 DDR PMU

[Chris Healy]

Reviewed-by: Chris Healy <healych at amazon.com>

On Tue, Nov 8, 2022 at 5:58 PM Jiucheng Xu <jiucheng.xu at amlogic.com> wrote:
>
> Add a user guide to show how to use DDR PMU to
> monitor DDR bandwidth on Amlogic G12 SoC
>
> Signed-off-by: Jiucheng Xu <jiucheng.xu at amlogic.com>
> ---
> Changes v8 -> v9:
>   - No change
>
> Changes v7 -> v8:
>   - No change
>
> Changes v6 -> v7:
>   - Drop the Reported-by tag
>   - Fix spelling error
>
> Changes v5 -> v6:
>   - No change
>
> Changes v4 -> v5:
>   - Fix building warning
>
> Changes v3 -> v4:
>   - No change
>
> Changes v2 -> v3:
>   - Rename doc name from aml-ddr-pmu.rst to meson-ddr-pmu.rst
>
> Changes v1 -> v2:
>   - Nothing was changed
> ---
>  Documentation/admin-guide/perf/index.rst      |  1 +
>  .../admin-guide/perf/meson-ddr-pmu.rst        | 70 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  3 files changed, 72 insertions(+)
>  create mode 100644 Documentation/admin-guide/perf/meson-ddr-pmu.rst
>
> diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst
> index 69b23f087c05..997a28e156c1 100644
> --- a/Documentation/admin-guide/perf/index.rst
> +++ b/Documentation/admin-guide/perf/index.rst
> @@ -17,3 +17,4 @@ Performance monitor support
>     xgene-pmu
>     arm_dsu_pmu
>     thunderx2-pmu
> +   meson-ddr-pmu
> diff --git a/Documentation/admin-guide/perf/meson-ddr-pmu.rst b/Documentation/admin-guide/perf/meson-ddr-pmu.rst
> new file mode 100644
> index 000000000000..15e93a751ced
> --- /dev/null
> +++ b/Documentation/admin-guide/perf/meson-ddr-pmu.rst
> @@ -0,0 +1,70 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +===========================================================
> +Amlogic SoC DDR Bandwidth Performance Monitoring Unit (PMU)
> +===========================================================
> +
> +There is a bandwidth monitor inside the DRAM controller. The monitor includes
> +4 channels which can count the read/write request of accessing DRAM individually.
> +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 the channel related events.
> +Each channel support using keywords as filter, which can let the channel
> +to monitor the individual IP module in SoC.
> +
> +The following keywords are the filter:
> +
> ++ arm             - DDR access request from CPU
> ++ vpu_read1       - DDR access request from OSD + VPP read
> ++ gpu             - DDR access request from 3D GPU
> ++ pcie            - DDR access request from PCIe controller
> ++ hdcp            - DDR access request from HDCP controller
> ++ hevc_front      - DDR access request from HEVC codec front end
> ++ usb3_0          - DDR access request from USB3.0 controller
> ++ hevc_back       - DDR access request from HEVC codec back end
> ++ h265enc         - DDR access request from HEVC encoder
> ++ vpu_read2       - DDR access request from DI read
> ++ vpu_write1      - DDR access request from VDIN write
> ++ vpu_write2      - DDR access request from di write
> ++ vdec            - DDR access request from legacy codec video decoder
> ++ hcodec          - DDR access request from H264 encoder
> ++ ge2d            - DDR access request from ge2d
> ++ spicc1          - DDR access request from SPI controller 1
> ++ usb0            - DDR access request from USB2.0 controller 0
> ++ dma             - DDR access request from system DMA controller 1
> ++ arb0            - DDR access request from arb0
> ++ sd_emmc_b       - DDR access request from SD eMMC b controller
> ++ usb1            - DDR access request from USB2.0 controller 1
> ++ audio           - DDR access request from Audio module
> ++ sd_emmc_c       - DDR access request from SD eMMC c controller
> ++ spicc2          - DDR access request from SPI controller 2
> ++ ethernet        - DDR access request from Ethernet controller
> +
> +
> +The following command is to show the total DDR bandwidth:
> +
> +  .. code-block:: bash
> +
> +      perf stat -a -e meson_ddr_bw/total_rw_bytes/ -I 1000 sleep 10
> +
> +This command will print the total DDR bandwidth per second.
> +
> +The following commands are to show how to use filter parameters:
> +
> +  .. 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
> +
> +The 1st command show how to use channel 1 to monitor the DDR bandwidth from ARM.
> +The 2nd command show using channel 2 to get the DDR bandwidth of GPU.
> +The 3rd command show using channel 3 to monitor the sum of ARM and GPU.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index eb63b9cbc149..5ed563368a48 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1055,6 +1055,7 @@ M:        Jiucheng Xu <jiucheng.xu at amlogic.com>
>  L:     linux-amlogic at lists.infradead.org
>  S:     Supported
>  W:     http://www.amlogic.com
> +F:     Documentation/admin-guide/perf/meson-ddr-pmu.rst
>  F:     drivers/perf/amlogic/
>  F:     include/soc/amlogic/
>
> --
> 2.25.1
>