Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756936Ab3IFPqb (ORCPT ); Fri, 6 Sep 2013 11:46:31 -0400 Received: from mail-ie0-f169.google.com ([209.85.223.169]:56200 "EHLO mail-ie0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753304Ab3IFPq3 (ORCPT ); Fri, 6 Sep 2013 11:46:29 -0400 MIME-Version: 1.0 In-Reply-To: <1831138.AvDtjG8RWn@vostro.rjw.lan> References: <26431283.HJCKsss0rt@vostro.rjw.lan> <1599165.8kjc3DtEzc@vostro.rjw.lan> <2228690.GcUDD3xFfP@vostro.rjw.lan> <1831138.AvDtjG8RWn@vostro.rjw.lan> Date: Fri, 6 Sep 2013 08:46:28 -0700 X-Google-Sender-Auth: kKgaUb7xJSA97w9VHQez1E6rojA Message-ID: Subject: Re: [PATCH 1/2] ACPI / hotplug / PCI: Avoid doing too much for spurious notifies From: Yinghai Lu To: "Rafael J. Wysocki" Cc: Alex Williamson , ACPI Devel Maling List , Bjorn Helgaas , LKML , Linux PCI , Jiang Liu , Mika Westerberg , "Kirill A. Shutemov" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2546 Lines: 62 On Fri, Sep 6, 2013 at 6:43 AM, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > Sometimes we may get a spurious device check or bus check notify for > a hotplug device and in those cases we should avoid doing all of the > configuration work needed when something actually changes. To that > end, check the return value of pci_scan_slot() in enable_slot() and > bail out early if it is 0. > > This turns out to help reduce the amount of diagnostic output from > the ACPIPHP subsystem and speed up boot on at least one system that > generates multiple device check notifies for PCIe ports during > boot. > > Reported-by: Alex Williamson > Signed-off-by: Rafael J. Wysocki > --- > drivers/pci/hotplug/acpiphp_glue.c | 35 +++++++++++++++++++++++++++-------- > 1 file changed, 27 insertions(+), 8 deletions(-) > > Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c > =================================================================== > --- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c > +++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c > @@ -542,12 +542,12 @@ static void __ref enable_slot(struct acp > struct acpiphp_func *func; > int max, pass; > LIST_HEAD(add_list); > + int nr_found; > > list_for_each_entry(func, &slot->funcs, sibling) > acpiphp_bus_add(func_to_handle(func)); > > - pci_scan_slot(bus, PCI_DEVFN(slot->device, 0)); > - > + nr_found = pci_scan_slot(bus, PCI_DEVFN(slot->device, 0)); > max = acpiphp_max_busnr(bus); > for (pass = 0; pass < 2; pass++) { > list_for_each_entry(dev, &bus->devices, bus_list) { > @@ -566,8 +566,11 @@ static void __ref enable_slot(struct acp > } > } > } > - > __pci_bus_assign_resources(bus, &add_list, NULL); > + /* Nothing more to do here if there are no new devices on this bus. */ > + if (!nr_found && (slot->flags & SLOT_ENABLED)) > + return; > + > acpiphp_sanitize_bus(bus); > acpiphp_set_hpp_values(bus); > acpiphp_set_acpi_region(slot); > why not just returning early before size bridges and assign unassign resources? Yinghai -- 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/