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On Wed, Jun 01, 2005 at 03:01:11PM +0900, YAMAMOTO Takashi wrote:
> hi,
>=20
> > If we start going down route of making the network stack even partially
> > SMP-safe, then I think the consensus on tech-kern is that we'll also
> > need to head in the direction of making all interrupts ordered; with
> > associated, hierarchically-ordered (spin)locks at each level.
>=20
> i didn't notice such a consensus.  can you give me a pointer?
>=20
> i don't see any needs to have all interrupts ordered.
> i won't object if you want to make them ordered as
> a transient convention, tho.

I thought the point was that interrupt handlers now will use spin locks to=
=20
protect their data. When an interrupt handler runs, it will run with SPL=20
set to block its interrupt on the CPU it's on, and it will also grab a=20
spinlock so that no other CPU services this interrupt (and also keep other=
=20
processing that would now block interrupts out of the data).

The locks will need to be ordered to avoid deadlock. As there will be a=20
correspondence between locks and SPL, we will then need to order SPL to=20
avoid deadlock.

Thus we will have a hierarchy to SPL levels.

Am I missing something?

Take care,

Bill

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