[yocto] Customize Number of Threads per Task?

[Chris Larson]

On Fri, May 17, 2013 at 1:53 AM, Paul Eggleton <
paul.eggleton at linux.intel.com> wrote:

> Hi Travis,
>
> On Friday 17 May 2013 00:40:51 Post, Travis wrote:
> > I’ve written a bitbake class that adds a custom task in-between
> do_configure
> > and do_compile, called ‘do_send_to_remote’. Is there any way for Yocto to
> > allow only one instance of this task to run at a time? I know I can set
> > BB_NUMBER_THREADS = 1, but that will slow down everything. Is there a way
> > to do something like: BB_NUMBER_THREADS[do_send_to_remote] = 1?
>
> I don't think we have anything quite like that, but we do have support for
> locking via a "lockfiles" parameter on a task function; e.g. from
> rootfs_rpm.bbclass:
>
> do_rootfs[lockfiles] += "${DEPLOY_DIR_RPM}/rpm.lock"
>
> That should ensure only one instance of the task's code gets to run at a
> time.
>

One could implement this through a custom bitbake scheduler. At one point I
had a scheduler which let you define a task flag to indicate which resource
it predominantly used (cpu, memory, network) and then let you define
per-resource maximum thread counts, but it was extremely naive, and didn't
improve overall performance much :\
-- 
Christopher Larson
clarson at kergoth dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Maintainer - Tslib
Senior Software Engineer, Mentor Graphics
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