| Message ID | 1831138.AvDtjG8RWn@vostro.rjw.lan (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Fri, Sep 6, 2013 at 6:43 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > 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 <alex.williamson@redhat.com> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > --- > 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-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday, September 06, 2013 08:46:28 AM Yinghai Lu wrote: > On Fri, Sep 6, 2013 at 6:43 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > > > 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 <alex.williamson@redhat.com> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > --- > > 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? Because we still need to do that even if pci_scan_slot() returns 0. There may be new devices down in the hierarchy and we need to look for them. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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);