lkml.org 
[lkml]   [2006]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] Multi-threaded device probing
Greg KH wrote:
> During the kernel summit, I was reminded by the wish by some people to
> do device probing in parallel, so I created the following patch. It
> offers up the ability for the driver core to create a new thread for
> every driver<->device probe call. To enable this, the driver needs to
> have the multithread_probe flag set to 1, otherwise the "traditional"
> sequencial probe happens.
>
> Note that this patch does not actually enable the threaded probe for any
> busses, as that's very dangerous at this point in time, without the
> different bus authors trying it out and verifying that it does work
> properly.
>
> I did enable this for both USB and PCI and shaved .4 seconds off of the
> boot time of my tiny little single processor laptop. The savings of my
> 4-way workstation is much greater, but things start to happen so fast we
> miss the root disk, as init starts before the disks are finished being
> initialized. I have some hacks to work around this right now, but I'll
> hold off on posting them before I make sure they work properly (breaking
> booting of people's machines isn't the best way to get them to accept
> new features...)
>
> Anyway, have fun playing around with this if you want, I'll be adding
> this to the next -mm, but you will have to enable the bit on your own if
> you want to see any speedups.
>

This is very interesting in the context of a few discussions I had at
OLS about klibc; there are people who would like initramfs to be
accessible *before* device probing is done, so that drivers can access
firmware and possible hotplug from the initramfs during the driver
initialization. We could even invoke (k)init at this point; this would
require a) having a system call or device that would allow kinit to
block until device probing was complete, and b) a way to handle
/dev/console -- there are several different ways to deal with it; it's
mostly a matter of picking a good one.

Note that we don't need device drivers for userspace -- we only need VM,
VFS and scheduler initialization.

Multithreaded device initialization is a great idea, especially since
many devices require delays during initialization, sometimes on the
order of seconds.

-hpa


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-07-25 23:35    [W:0.301 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site