Limiting Yocto Memory Usage

Limiting Yocto Memory Usage

[Luis Merayo]

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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?

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.

Regards,

Luis

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Re: [yocto] Limiting Yocto Memory Usage

[Randy MacLeod]

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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.

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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