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PCI: enable driver multi-threaded probe

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This provides a build and run-time option to turn on multhreaded probe
for all PCI drivers.  It can cause bad problems on multi-processor
machines that take a while to find their root disks, and play havoc on
machines that don't use persistant device names for block or network
devices.

But it can cause speedups on some machines, my tiny laptop's boot goes
up by 0.4 seconds, and my desktop boots up several seconds faster.

Use at your own risk!!!

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Greg Kroah-Hartman 2006-07-18 10:59:59 -07:00
parent d779249ed4
commit 0f397f8650
2 changed files with 36 additions and 0 deletions
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25
drivers/pci/Kconfig
View File

@ -17,6 +17,31 @@ config PCI_MSI
If you don't know what to do here, say N.
config PCI_MULTITHREAD_PROBE
bool "PCI Multi-threaded probe (EXPERIMENTAL)"
depends on PCI && EXPERIMENTAL
help
Say Y here if you want the PCI core to spawn a new thread for
every PCI device that is probed. This can cause a huge
speedup in boot times on multiprocessor machines, and even a
smaller speedup on single processor machines.
But it can also cause lots of bad things to happen. A number
of PCI drivers can not properly handle running in this way,
some will just not work properly at all, while others might
decide to blow up power supplies with a huge load all at once,
so use this option at your own risk.
It is very unwise to use this option if you are not using a
boot process that can handle devices being created in any
order. A program that can create persistant block and network
device names (like udev) is a good idea if you wish to use
this option.
Again, use this option at your own risk, you have been warned!
When in doubt, say N.
config PCI_DEBUG
bool "PCI Debugging"
depends on PCI && DEBUG_KERNEL

11
drivers/pci/pci-driver.c
View File

@ -17,6 +17,16 @@
* Registration of PCI drivers and handling of hot-pluggable devices.
*/
/* multithreaded probe logic */
static int pci_multithread_probe =
#ifdef CONFIG_PCI_MULTITHREAD_PROBE
1;
#else
0;
#endif
__module_param_call("", pci_multithread_probe, param_set_bool, param_get_bool, &pci_multithread_probe, 0644);
/*
* Dynamic device IDs are disabled for !CONFIG_HOTPLUG
*/
@ -408,6 +418,7 @@ int __pci_register_driver(struct pci_driver *drv, struct module *owner)
drv->driver.bus = &pci_bus_type;
drv->driver.owner = owner;
drv->driver.kobj.ktype = &pci_driver_kobj_type;
drv->driver.multithread_probe = pci_multithread_probe;
spin_lock_init(&drv->dynids.lock);
INIT_LIST_HEAD(&drv->dynids.list);