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

[xiangyu.chen@eng.windriver.com]

On 11/7/22 10:27, Xiangyu Chen wrote:
>
> On 11/7/22 10:18, Khem Raj wrote:
>> CAUTION: This email comes from a non Wind River email account!
>> Do not click links or open attachments unless you recognize the 
>> sender and know the content is safe.
>>
>> On Sun, Nov 6, 2022 at 5:21 PM Xiangyu Chen 
>> <xiangyu.chen@windriver.com> wrote:
>>>
>>> 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?
>> My concern is that will it be so for all aarch64 machines ?
>
Please discard this thread, we also found that the rng-tools high cpu 
usage not only on ARM64 but also on ARM32 platform(also include 
qemuarm/qemuarm64), it's a common issue on ARM platform.

A new patch has been sent to list as below link, tested in my local 
setup, thanks.


https://lists.openembedded.org/g/openembedded-core/message/173266

https://patchwork.yoctoproject.org/project/oe-core/patch/20221115081819.761176-1-xiangyu.chen@eng.windriver.com/



Thanks,

Xiangyu

> I tested two aarch64 platforms on my hand, zynqmp and raspi4, the 
> rng-tools behavior is the same, when service start, the jitter random 
> generator would load full cpu cores load. It would cause other 
> services take long time to start. I also checked another linux 
> distribution, so far, only Alpine Linux processed this issue and it 
> applied those configurations on all aarch64 platforms.
>
>
> Thanks,
>
> Xiangyu
> 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"
>>
>>
>>
>
>
>
> -=-=-=-=-=-=-=-=-=-=-=-
> Links: You receive all messages sent to this group.
> View/Reply Online (#172821): https://lists.openembedded.org/g/openembedded-core/message/172821
> Mute This Topic: https://lists.openembedded.org/mt/94701000/7175143
> Group Owner: openembedded-core+owner@lists.openembedded.org
> Unsubscribe: https://lists.openembedded.org/g/openembedded-core/unsub [xiangyu.chen@windriver.com]
> -=-=-=-=-=-=-=-=-=-=-=-
>