This patch adds a quick check for the driver<->device match before
taking the locks and doin gthe expensive checks. Taking the lock hurts
in asynchronous boot context where the device lock gets hit; one of the
init functions takes the lock and goes to do an expensive hardware init;
the other init functions walk the same PCI list and get stuck on the
lock as a result.
For the common case, we can know there's no chance whatsoever of a match
if the device isn't in the drivers ID table... so this patch does that
check as a best-effort-avoid-the-lock approach.
Bootcharts for before and after can be seen at
http://www.fenrus.org/before.svghttp://www.fenrus.org/after.svg
Note the long time "agp_ali_init" takes in the first graph; my laptop
doesn't even have an ALI chip in it! (the bootgraphs look a bit
dissimilar, but that's the point, the first one has a bunch of arbitrary
delays in it that cause it to look very different)
This reduces my kernel boot time by about 20%
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
6cd4958609
