nRF5340: RAM consumption on net-core

[Yanpengwu]

Hi Support team,

The RAM consumption on the net-core of nRF5340 is a little high. I tried to manage the buffer and stack and minimized the configuration in prj.conf, but still a little high.

Could you help give some suggestions for the RAM reducing, especially on Link Time Optimization and compiler setting sides?

Thank you very much.

Best regards,

Yanpeng Wu

[Håkon Alseth]

Hi,

 

Unless explicitly stated, the default optimization is for size.

Unfortunately, LTO is not possible to enable on the whole project, but you can enable it on your locally included src files, like this:

 https://github.com/nrfconnect/sdk-nrf/blob/v2.5.2/applications/asset_tracker_v2/CMakeLists.txt#L43-L45

Just an FIY: LTO may not be effective on RAM usage, actually; it can reduce the .RO usage while increasing the RAM usage in some scenarios.

 

You could run the thread analyzer to see if there's any of the stacks that are excessively high:

https://docs.zephyrproject.org/latest/services/debugging/thread-analyzer.html

 

How much headroom do you need? Have you disabled uart/coredump/log/console etc?

 

Kind regards,

Håkon

[Yanpengwu]

Hi Håkon,

Thank you for your guidance, I will try it.

Currently, I enabled log, console and RTT, UART was used for the communication between a cellular modem and net-core of nRF5340.
the main function of net-core is to use the modem driver, net stack, mqtt to send and receive data.

if I use 'ninja ram_report', I can see ZEPHYR_BASE consumed 52k(89.66%), the biggest parts are net and ip subsystem (32k)
now the compiled result is
Memory region Used Size Region Size %age Used
FLASH: 181524 B 256 KB 69.25%
RAM: 58512 B 64 KB 89.28%
SRAM1: 0 GB 64 KB 0.00%
IDT_LIST: 0 GB 2 KB 0.00%

Best regards,
Yanpeng Wu

[Håkon Alseth]

Hi,

 

Yanpengwu said:

the biggest parts are net and ip subsystem (32k)

This makes sense, as the bluetooth part uses the net subsys for buffering.

You still have a bit of head-room. Are you planning of adding more features to the net-core?

 

Kind regards,

Håkon

[Yanpengwu]

Hi Håkon,

I'm not using the Bluetooth, I'm using the the cellular modem and MQTT on the net-core. Next step I will add the TLS. I think I need to optimize the RAM usage from the configuration and application data structures in the next stage.

I closed this ticket and I will ask again when I meet the specific questions. Thank you very much.

Best regards,

Yanpeng Wu