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* disabling timer interrupt until (system_state >= SYSTEM_RUNNING)
@ 2020-02-06 17:25 William Tambe
  2020-02-06 18:26 ` Greg KH
  0 siblings, 1 reply; 3+ messages in thread
From: William Tambe @ 2020-02-06 17:25 UTC (permalink / raw)
  To: kernelnewbies

Since voluntary preemption is used during kernel booting, is it safe
to disable timer interrupt until (system_state >= SYSTEM_RUNNING) ?

Wouldn't it speed up booting ?

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: disabling timer interrupt until (system_state >= SYSTEM_RUNNING)
  2020-02-06 17:25 disabling timer interrupt until (system_state >= SYSTEM_RUNNING) William Tambe
@ 2020-02-06 18:26 ` Greg KH
  2020-02-07  0:53   ` William Tambe
  0 siblings, 1 reply; 3+ messages in thread
From: Greg KH @ 2020-02-06 18:26 UTC (permalink / raw)
  To: William Tambe; +Cc: kernelnewbies

On Thu, Feb 06, 2020 at 12:25:27PM -0500, William Tambe wrote:
> Since voluntary preemption is used during kernel booting, is it safe
> to disable timer interrupt until (system_state >= SYSTEM_RUNNING) ?
> 
> Wouldn't it speed up booting ?

Try it and see!

:)

Seriously, think about what needs to be done by the system during boot
time.  Hardware is initialized, threads are spawned, lots of other
things are going on.  It's not just one single process until that system
state change happens by any means.

thanks,

greg k-h

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: disabling timer interrupt until (system_state >= SYSTEM_RUNNING)
  2020-02-06 18:26 ` Greg KH
@ 2020-02-07  0:53   ` William Tambe
  0 siblings, 0 replies; 3+ messages in thread
From: William Tambe @ 2020-02-07  0:53 UTC (permalink / raw)
  To: Greg KH; +Cc: kernelnewbies

On Thu, Feb 6, 2020 at 2:24 PM Greg KH <greg@kroah.com> wrote:
>
> On Thu, Feb 06, 2020 at 12:25:27PM -0500, William Tambe wrote:
> > Since voluntary preemption is used during kernel booting, is it safe
> > to disable timer interrupt until (system_state >= SYSTEM_RUNNING) ?
> >
> > Wouldn't it speed up booting ?
>
> Try it and see!
>
> :)
>
> Seriously, think about what needs to be done by the system during boot
> time.  Hardware is initialized, threads are spawned, lots of other
> things are going on.  It's not just one single process until that system
> state change happens by any means.

I am doing kernel porting work and I am able to see Linux booting all
the way to init without timer interrupt; despite kernel thread being
spawned during booting.

Perhaps I may start seeing issues if a module spawn a thread that
never voluntarily preempt itself ?

>
> thanks,
>
> greg k-h

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Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2020-02-06 17:25 disabling timer interrupt until (system_state >= SYSTEM_RUNNING) William Tambe
2020-02-06 18:26 ` Greg KH
2020-02-07  0:53   ` William Tambe

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