Messages in this thread Patch in this message | | | Date | Sun, 14 Sep 2008 08:32:06 -0700 | From | Arjan van de Ven <> | Subject | [PATCH] device model: Do a quickcheck for driver binding before doing an expensive check |
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From: Arjan van de Ven <arjan@linux.intel.com> Subject: [PATCH] device model: Do a quickcheck for driver binding before doing an expensive check
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.svg http://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> --- drivers/base/dd.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 3ac443b..20febc0 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -257,6 +257,9 @@ static int __driver_attach(struct device *dev, void *data) * is an error. */ + if (drv->bus->match && !drv->bus->match(dev, drv)) + return 0; + if (dev->parent) /* Needed for USB */ down(&dev->parent->sem); down(&dev->sem); -- 1.5.5.1
-- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org
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