[opensuse-factory] Multi-threaded PCI device probing now in FACTORY kernel
I've recently added the ability to do multi-threaded PCI device probing to the latest kernel builds that have already shown up in the FACTORY tree. To enable this, on the kernel boot line add the following: pci_multithread_probe=1 Note, here's the warning that I give to anyone who wants to try this option out: Enable this option 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, you have been warned about this, but I would like to hear about any success or failure reports for people trying this out. I do know that some video-for-linux devices (like DVB ones), do not play well with this system, and if you have more than one PCI sound card in your machine, it can confuse the ordering of them. Also, some SATA drive controllers don't like this option at all, and just refuse to be found entirely (ata_piix is known for this), preventing you to boot from those machines at times. I've heard some odd rumors that the intel wireless drivers don't like this either, but I can't duplicate this on my machines, although I don't have a dual-core box to test it out on... Have fun! greg k-h --------------------------------------------------------------------- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-factory+help@opensuse.org
Hi Greg, Greg KH wrote:
Again, you have been warned about this, but I would like to hear about any success or failure reports for people trying this out.
Works fine here (Intel Pentium M processor 1.60GHz), but I can't see any speedup. Normally, I need 57 seconds from bootloader to kdm, with pci_multithread_probe=1 I need 58 seconds. Such a small change in boot time is just noise. Regards, Carl-Daniel --------------------------------------------------------------------- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-factory+help@opensuse.org
On Fri, Sep 29, 2006 at 09:02:06PM +0200, Carl-Daniel Hailfinger wrote:
Hi Greg,
Greg KH wrote:
Again, you have been warned about this, but I would like to hear about any success or failure reports for people trying this out.
Works fine here (Intel Pentium M processor 1.60GHz), but I can't see any speedup.
For laptops, with few devices, the potential speedup is usually pretty small, sorry. Larger servers, with lots of PCI devices and multiple processors should show some kind of speedup.
Normally, I need 57 seconds from bootloader to kdm, with pci_multithread_probe=1 I need 58 seconds. Such a small change in boot time is just noise.
Heh, yes. It's a bit easier to just time the 'boot to init' time for something like this instead, because this will not change anything after init starts up. thanks, greg k-h --------------------------------------------------------------------- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-factory+help@opensuse.org
participants (2)
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Carl-Daniel Hailfinger
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Greg KH