On Fri, 2012-10-05 at 09:16 -0600, Bjorn Helgaas wrote:
> On Fri, Oct 5, 2012 at 8:54 AM, Nathan Zimmer <nzimmer@xxxxxxx> wrote:
> > On 10/05/2012 09:14 AM, Joe Perches wrote:
> >> On Fri, 2012-10-05 at 08:55 -0500, Nathan Zimmer wrote:
> >>> On 10/04/2012 11:37 AM, Joe Perches wrote:
> >>>> On Thu, 2012-10-04 at 11:02 -0500, Nathan Zimmer wrote:
> >>>>> At many of our customer sites the log level is set to KERN_DEBUG. It
> >>>>> helps avoid reboots due to operator impatience. Machines this large
> >>>>> take significantly longer then typical to boot and seeing the extra
> >>>>> messages reassures them that the kernel isn't hung.
> >>>>
> >>>> That argues for adding some KERN_INFO "still booting" messages
> >>>> not logging unnecessary KERN_DEBUG messages.
> >>>>
> >>> Actually I would think that argues for reducing boot times on these
> >>> large systems.
> >>
> >> Right.
> >>
> >> That's an independent argument, but sure, go ahead
> >> and do that too.
[]
> > Here is output for my workstation a simple 4x box
> >
> > -bash-4.1$ dmesg | grep "type [0-9][0-9] class" | wc
> > 12 108 804
> > -bash-4.1$ dmesg | wc
> > 744 6359 49474
> > Here is some output from one of the biggest boxes.
> > -bash-4.1$ dmesg | wc
> > 26503 235414 1811651
> > -bash-4.1$ dmesg | grep "type [0-9][0-9] class" | wc
> > 12085 108765 821780
>
> Many vendors don't expose host bridges that lead to the CPU-related
> PCI devices because they don't want the OS to muck with them. We
> currently blindly probe for these in domain 0, so we find them anyway
> (I think we should change this behavior).
>
> I'd guess that having all these CPU-related devices around also really
> clutters up "lspci" output, and of course, consumes memory for all the
> pci_dev structs in the kernel. It takes some time to enumerate them
> all, so avoiding that would speed up boot somewhat.
>
> So I wonder if it might be more useful to figure out how to avoid
> enumerating those devices in the first place? The first step would be
> to stop exposing PNP0A03/PNP0A08 host bridges that lead to them. As I
> mentioned, we currently will probably find them anyway via blind
> probing. You might be able to avoid that if you could place them in a
> PCI domain other than 0
And in the meantime, maybe something like this and not logging
at KERN_DEBUG when using verbose_boot would help avoid impatient
operator reboots.
drivers/pci/hotplug/sgi_hotplug.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/pci/hotplug/sgi_hotplug.c b/drivers/pci/hotplug/sgi_hotplug.c
index f64ca92..b3abd1a 100644
--- a/drivers/pci/hotplug/sgi_hotplug.c
+++ b/drivers/pci/hotplug/sgi_hotplug.c
@@ -368,6 +368,10 @@ static int enable_slot(struct hotplug_slot *bss_hotplug_slot)
}
}
+ if (some_verbose_boot_flag)
+ dev_info(&slot->pci_bus->self->dev, "Testing slot %d\n",
+ slot->device_num + 1);
+
num_funcs = pci_scan_slot(slot->pci_bus,
PCI_DEVFN(slot->device_num + 1, 0));
if (!num_funcs) {
--
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