[bitbake-devel] [PATCH] build: Add BB_TASK_NICE_LEVEL to task code

[Paul Eggleton]

On Friday 20 September 2013 11:29:47 Richard Purdie wrote:
> On Linux its not possible for processes to regain a previous nice level
> after it has changed. Its therefore not possible to have a core low
> priority and then raise the priorities of individual tasks.
> 
> This variable allows us to do something like:
> 
> BB_TASK_NICE_LEVEL = "5"
> BB_TASK_NICE_LEVEL_task-testimage = "0"
> 
> to give priority to specific tasks which the BB_NICE_LEVEL functionality
> doesn't give us the option of.
> 
> Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
> ---
> diff --git a/bitbake/lib/bb/build.py b/bitbake/lib/bb/build.py
> index 8aec699..9addd71 100644
> --- a/bitbake/lib/bb/build.py
> +++ b/bitbake/lib/bb/build.py
> @@ -346,6 +346,13 @@ def _exec_task(fn, task, d, quieterr):
>      if not tempdir:
>          bb.fatal("T variable not set, unable to build")
> 
> +    # Change nice level if we're asked to
> +    nice = localdata.getVar("BB_TASK_NICE_LEVEL", True)
> +    if nice:
> +        curnice = os.nice(0)
> +        nice = int(nice) - curnice
> +        logger.debug(1, "Renice to %s " % os.nice(nice))

It's a matter of style to be sure, but I think it's better not to have debug 
statements that do more than just printing debug output - could the latter be 
split onto two lines? Then it's easy to tell what's being done.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre