Re: [OE-Core][master][kirkstone][PATCH V2] rng-tools: Add Arm aarch64 CPU specific configuration to address excessive CPU usage on startup

[Xiangyu Chen <xiangyu.chen@windriver.com>]

On 11/1/22 09:48, Xiangyu Chen wrote:
> With the default jitter options aarch64 CPU-based devices typically experience continuous
> high CPU utilisation for several minutes after rngd starts.
>
> Accoring to the rng-tools issue #150[1] and comments[2],in order to address this,
> the following configuration changes have been made, those configurations
> also can be found on Alpine Linux[3]:
>
> - reduce the number of threads used to 1 in total, rather than 1 per core.
> - reduce the buffer size from 16535 to 4133 which reduces the time taken
>    to fill the buffer (and so reduces the duration of CPU load).
>
> [1] https://github.com/nhorman/rng-tools/issues/150
> [2] https://github.com/nhorman/rng-tools/issues/150#issuecomment-953079212
> [3] https://git.alpinelinux.org/aports/tree/main/rng-tools/rngd.confd-arm
>
> Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
> ---
> Changes in V2:
>    *put the aarch64 specific default file in meta/recipes-support/rng-tools/rng-tools/aarch64

Friendly ping. Is there any more concern on this?


Thanks,

Xiangyu

> ---
>   .../rng-tools/rng-tools/aarch64/default               | 11 +++++++++++
>   1 file changed, 11 insertions(+)
>   create mode 100644 meta/recipes-support/rng-tools/rng-tools/aarch64/default
>
> diff --git a/meta/recipes-support/rng-tools/rng-tools/aarch64/default b/meta/recipes-support/rng-tools/rng-tools/aarch64/default
> new file mode 100644
> index 0000000000..5a2fbcc9ef
> --- /dev/null
> +++ b/meta/recipes-support/rng-tools/rng-tools/aarch64/default
> @@ -0,0 +1,11 @@
> +# With the default jitter options Arm CPU-based devices typically experience
> +# continuous high CPU utilisation for several minutes after rngd starts.
> +# See https://gitlab.alpinelinux.org/alpine/aports/-/issues/13035 and
> +# https://github.com/nhorman/rng-tools/issues/150
> +# In order to address this the following configuration changes have been made:
> +#
> +#   - reduce the number of threads used to 1 in total, rather than 1 per core.
> +#   - reduce the buffer size from 16535 to 4133 which reduces the time taken
> +#     to fill the buffer (and so reduces the duration of CPU load).
> +#
> +EXTRA_ARGS="-r /dev/hwrng -O jitter:buffer_size:4133 -O jitter:refill_thresh:4133 -O jitter:thread_count:1"
>
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