On Thu, 2005-06-02 at 14:36, Jonathan Stone wrote:
> Bill STudenmund writes:
> 
> >On Wed, Jun 01, 2005 at 03:01:11PM +0900, YAMAMOTO Takashi wrote:
> [[ Jonathan claims a consensus for ordering of SPLs]]
> 
> >> 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
> >protect their data. When an interrupt handler runs, it will run with SPL
> >set to block its interrupt on the CPU it's on, and it will also grab a
> >spinlock so that no other CPU services this interrupt (and also keep other
> >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
> >correspondence between locks and SPL, we will then need to order SPL to
> >avoid deadlock.
> >
> >Thus we will have a hierarchy to SPL levels.
> >
> >Am I missing something?

Mhhh - not all locks need to be strongly ordered.
Maybe we can do the same for spl levels?

> Hi Bill,
> 
> That's pretty much the argument I was making in late 2003/early 2004;
> thank you for a clear concise statement.   I see Yamamoto-san said, in reply:
> 
> 
> >i have objection if you implies global IPLs.
> >(like your original proposal in 2003)
> 
> 
> Now that leaves me confused! I thought what Bill outlines is, in
> essence, what I proposed in late 2003. Yamamoto-san, do they sound
> like the same thing to you? Do we have a consensus for it (or for one
> or other, if they are different)?

Global as in contrast to per CPU?
I think we all agree that we want per CPU. Right?
Do you have a link handy to your 2003 proposal? 

Stephan