Re: [yocto] Limiting Yocto Memory Usage

[Ferry Toth <fntoth@gmail.com>]

Hi

Op 28-07-2026 om 09:30 schreef Ferry Toth:
> Hi,
> 
> Op 14-07-2026 om 23:33 schreef Randy MacLeod:
>> Hi Luis,
>>
>> On 2026-07-10 17:26, Luis Merayo via lists.yoctoproject.org wrote:
>>> Hi,
>>>
>>> I would like to know if there is a way to limit Bitbake's Memory 
>>> usage to a specific percentage of the available RAM. For example, can 
>>> the Yocto build be limited to use a maximum of 70% of RAM?
>> Not without using a container to do the build.
>>>
>>> Could these three variables achieve this?
>>>
>>> BB_PRESSURE_MAX_CPU <https://docs.yoctoproject.org/dev/ref-manual/ 
>>> variables.html#term-BB_PRESSURE_MAX_CPU>, BB_PRESSURE_MAX_IO 
>>> <https:// docs.yoctoproject.org/dev/ref-manual/variables.html#term- 
>>> BB_PRESSURE_MAX_IO> , BB_PRESSURE_MAX_MEMORY <https:// 
>>> docs.yoctoproject.org/dev/ref-manual/variables.html#term- 
>>> BB_PRESSURE_MAX_MEMORY>
>>>
>>> I see the range for these variables is from 1 to 1000000, so I would 
>>> like to understand if there is a way to specify their values as a 
>>> function of the available RAM.
>> No, there is only pressure when resources are over-commited so if you 
>> have free memory, there's no over-commit.
>> https://docs.kernel.org/accounting/psi.html
>>
>> That's the design intent of the bitbake PRESSURE regulation system.
>>
>> There are plans to work on additional build system regulation.
>>
>> The first idea is to use the jobserver design:
>> https://lore.kernel.org/openembedded-core/?q=GNU+AND+jobserver+ 
>> +AND+f%3Amacleod
>> and that would indirectly limit memory consumption since there would 
>> be fewer instances of gcc / rustc / ... running
>> at once.
> 
> I do that, since 2 years or so. https://github.com/htot/meta-intel- 
> edison/commits/whinlatter/
> 
> In principle you need to catch the call to make and ninja (to force them 
> to use the jobserver) and patch bitbake (see setup.sh) to act as a 
> jobserver.
> 
> Now got it working on wrynose, still need to push that. Maybe later 
> today.With wrynose ninja has support for jobserver so doesn't need 
> patching, just a bbappend.

Pushed my wrynose branch now: 
https://github.com/htot/meta-intel-edison/tree/wrynose

> With this you can limit the number of compile jobs. On my builds I found 
> g++ compiles are the heaviest, about 1GB RAM each. So, with 16 cores I 
> need 16 GB.
> Separately I found linking nodejs takes 5 x 5GB (5 jobs linking with 
> LTO?). So, I limited that to just one (since both nodejs and nodejs- 
> native can be built at the same time).
> 
> I'm not building rust so there may be other bottlenecks to resolve.
> 
>> There's also an even less clear idea about being able to restrict the 
>> build by specifying memory usage.
>> That shouldn't be too hard to implement in bitbake in the same point 
>> where the pressure checks happen.
>> Are you interested in working on that ?
>>
>> There are of course other levers to pull to reduce CPU/memory 
>> consumption:
>> https://docs.yoctoproject.org/dev-manual/limiting-resources.html
>>
>> Have you tried them ?
>>
>>
>>>
>>> Regards,
>>>
>>> Luis
>>>
>>>
>>>
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>>
>> -- 
>> # Randy MacLeod
>> # Wind River Linux
>>
> 
>