On Tue, May 29, 2007 at 09:47:53AM +0800, Yang Sheng wrote: > On Tuesday 29 May 2007 06:52, Randy Dunlap wrote: > > On Mon, 28 May 2007 15:03:10 +0800 Yang Sheng wrote: > > > Why we need this: > > > > > > It can speed up the calling of initcalls, especially useful for some > > > embed device. > > > > Can you give concrete example(s) of why we need this? > > Any real configs/hardware where it helps and how much it helps. > > > > We didn't got the precise data at hand now, because we should build a > complete > stable initcall dependence relationship for it, but we can't do it now. > > But we have done a relative stable test in a common x86_64 machine, with 2 > threads and one dependence relation(pnpacpi_init depends on pnp_init and > acpi_init). The result is the time spending on initcall calling reducing > from > about _5s_ to _2s_ (make the kernel with the defconfig). We analyzed the > dmesg and found the most of time was save by run ide_generic_init and > piix_init in parallel. > > Of course the dependence in the test case is not sufficient, but the effect > is > shown. > > We think this patch would be very useful in some embed deviced which > requires > fast boot speed. Some server may benefit too because of it's long time for > device initiation.
If we decide to do this, we should also introduce a way to disable it at runtime with initcall=noparallel or something. Why? Because right now when people say "my computer hangs during bootup" we can ask them to boot with initcall_debug and usually find out the last thing it did before it locked up. If we parallelise this, the output will be a lot harder to decipher. Dave -- http://www.codemonkey.org.uk - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/