Thought about speeding up startup...

Matt Zimmerman mdz at
Thu Oct 21 18:11:27 CDT 2004

On Thu, Oct 21, 2004 at 11:49:41PM +0100, Matthew Garrett wrote:

> The actual scanning of hardware that occurs when hotplug runs is fairly
> fast - it's able to use information that the kernel already has. The
> delay is in loading the drivers, rather than anything else. The most
> significant problem with hotplug is the way it insists on trying to load
> drivers that aren't actually appropriate for the hardware - making
> hotplug more intelligent about what it tries would be a useful
> improvement.

In Oxford, I did some primitive profiling of this, and a huge part of the
delay is actually parsing out the (large) pcimap file using only the shell.
I believe it was about 300ms per PCI device, which adds up to a significant
amount of time.  Most of the modules are actually fairly quick to load.
The whole pipeline is started up and stopped again for each device; I have
17 PCI devices in my laptop, and 11 in my desktop.

The trouble is that hotplug runs so early, that it can't rely on having much
available in terms of useful programming languages or other

 - mdz

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