From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757657AbYJPR0E (ORCPT ); Thu, 16 Oct 2008 13:26:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756380AbYJPROr (ORCPT ); Thu, 16 Oct 2008 13:14:47 -0400 Received: from kroah.org ([198.145.64.141]:46999 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756360AbYJPROq (ORCPT ); Thu, 16 Oct 2008 13:14:46 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Arjan van de Ven , Alan Stern , Greg Kroah-Hartman Subject: [PATCH 29/46] device model: Do a quickcheck for driver binding before doing an expensive check Date: Thu, 16 Oct 2008 10:10:30 -0700 Message-Id: <1224177047-11859-29-git-send-email-gregkh@suse.de> X-Mailer: git-send-email 1.6.0.2 In-Reply-To: <20081016170954.GA11824@kroah.com> References: <20081016170954.GA11824@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arjan van de Ven 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 Cc: Alan Stern Signed-off-by: Greg Kroah-Hartman --- 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); -- 1.6.0.2