Re: [GIT PULL] On-demand device probing

[Mark Brown]

On Wed, Oct 21, 2015 at 08:59:51AM -0700, Frank Rowand wrote:
> On 10/19/2015 5:34 AM, Tomeu Vizoso wrote:

> > To be clear, I was saying that this series should NOT affect total
> > boot times much.

> I'm confused.  If I understood correctly, improving boot time was
> the key justification for accepting this patch set.  For example,
> from "[PATCH v7 0/20] On-demand device probing":
> 
>    I have a problem with the panel on my Tegra Chromebook taking longer
>    than expected to be ready during boot (Stéphane Marchesin reported what
>    is basically the same issue in [0]), and have looked into ordered
>    probing as a better way of solving this than moving nodes around in the
>    DT or playing with initcall levels and linking order.
> 
>    ...
> 
>    With this series I get the kernel to output to the panel in 0.5s,
>    instead of 2.8s.

Overall boot time and time to get some individual built in component up
and running aren't the same thing - what this'll do is get things up
more in the link order of the leaf consumers rather than deferring those
leaf consumers when their dependencies aren't ready yet.

> While not as dramatic as your results, they are somewhat supportive.
> What has changed your assessment that the on-demand device probing
> patches will give a big boot performance increase?  Do you have
> new data or analysis?

See above, my understanding was that the performance improvements were
more around improved control/predictability/handwave of the boot
ordering rather than total time.

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