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SubjectRe: long boot delays caused by 070ad7e7 floppy change
On Tue, Jul 03, 2012 at 12:12:53PM -0700, Linus Torvalds wrote:
> On Tue, Jul 3, 2012 at 11:58 AM, Andi Kleen <andi@firstfloor.org> wrote:
> >
> > [ 2.496493] calling floppy_init+0x0/0xe46 @ 1
> > [ 2.511303] floppy0: lock_fdc: -1 (out of 8)
> > [ 2.511346] floppy0: __reschedule_timeout: setting timeout to 750
>
> Ahhah. And you have CONFIG_HZ250 set, don't you?

Yes I do.

>
> So it's actually asking for a 3-second timeout like it should.
>
> > [ 2.511372] floppy0: reschedule timeout lock fdc
> > [ 22.501757] floppy0: reschedule timeout do wakeup
>
> But that actual timeout is too damn reliably pretty much exactly 20s
> for it to be anything else.
>
> I wonder if 'fd_timeout' had been previously queued already with the
> 20s timeout, and not canceled. So then the new queuing of a 3-second
> timeout doesn't actually do anything, because the
> WORK_STRUCT_PENDING_BIT is still set.
>
> So maybe we're missing a cancel somewhere.
>
> What happens if you add a
>
> cancel_delayed_work(&fd_timeout);
>
> to before the queue_delayed_work() in __reschedule_timeout()? Does
> that possibly make the delay really be 3 seconds?

That works. Patch cuts it down to 3s as before

Tested-by: Andi Kleen <ak@linux.intel.com>

(and with the async probe patch I posted earlier the kernel
boot time goes down by ~1s from 14 to 13ish)

-Andi

With Linus patch:

[ 2.492449] calling floppy_init+0x0/0xe46 @ 1
[ 2.507259] floppy0: lock_fdc: -1 (out of 8)
[ 2.507304] floppy0: __reschedule_timeout: setting timeout to 750
[ 2.507330] floppy0: reschedule timeout lock fdc
[ 5.509642] floppy0: reschedule timeout do wakeup
[ 5.509683] floppy0: no floppy controllers found
[ 5.509796] initcall floppy_init+0x0/0xe46 returned -19 after 2952148
usecs
[ 5.509826] calling brd_init+0x0/0x1ce @ 1


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