Messages in this thread | | | From | Sheng Yang <> | Subject | Re: [RFC PATCH]Multi-threaded Initcall with dependence support | Date | Mon, 4 Jun 2007 09:06:39 +0800 |
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On Friday 01 June 2007 04:26, Dave Jones wrote: > 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.
Thank you for the advice. I will introduce a parameter to do this.
But what's about idea itself? I don't know whether people like this... It required a little more work on initcall writing.
Maybe we could limit the multithread part in device_initcall? For it seems the most time consumed here, and the others in total just less than 1s(at least on my machine).
Thanks. -- regards Yang, Sheng - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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