[apparmor] [PATCH] [parser] Fix jobs not scaling up to meet available resources when cpus are brought online during compilation

[Christian Boltz]

Hello,

Am Dienstag, 5. April 2016, 13:22:19 CEST schrieb Seth Arnold:
> On Tue, Apr 05, 2016 at 12:37:07PM -0700, John Johansen wrote:
> > Enable dynamically scaling max jobs if new resources are brought
> > online
> > 
> > BugLink: http://bugs.launchpad.net/bugs/1566490
> > 
> > This patch enables to parser to scale the max jobs if new resources
> > are being brought online by the scheduler.
> > 
> > It only enables the scaling check if there is a difference between
> > the maximum number of cpus (CONF) and the number of online (ONLN)
> > cpus.
> > 
> > Instead of checking for more resources regardless, of whether the
> > online cpu count is increasing it limits its checking to a maximum
> > of MAX CPUS + 1 - ONLN cpus times. With each check coming after
> > fork spawns a new work unit, giving the scheduler a chance to bring
> > new cpus online before the next check.  The +1 ensures the checks
> > will be done at least once after the scheduling task sleeps waiting
> > for its children giving the scheduler an extra chance to bring cpus
> > online.

Will it also reduce the number of processes if some CPUs are sent to 
vacation?

> > Signed-off-by: John Johansen <john.johansen at canonical.com>
> 
> This feels more complicated than it could be but I must admit I can't
> suggest any modifications to the algorithm to simplify it.

It sounds too simple, and it might start too many jobs in some cases, 
but - why not use the total number of CPUs from the beginning instead of 
the currently online CPUs?

The only possible disadvantage is running "too many" jobs - would that 
do any harm?


Regards,

Christian Boltz
-- 
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