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From: Walt Drummond <drummond@engr.valinux.com>
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Date: Mon, 16 Apr 2001 09:00:24 -0700
To: "Hubertus Franke" <frankeh@us.ibm.com>
Cc: george anzinger <george@mvista.com>,
        Linux Kernel List <linux-kernel@vger.kernel.org>,
        lse-tech@lists.sourceforge.net
Subject: Re: [Lse-tech] Bug in sys_sched_yield
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Hubertus Franke writes:
> I think that all data accesses particularly to __aligned_data
> should be performed through logical ids. There's a lot of remapping
> going on, due to the mix of logical and physical IDs.
> 
> If indeed the physical numbers are sparse (like we had on a 4x4
> NUMA system) then indexing doesn't work anyway.

This is exactly right.  On IA64, we have to hide the physical
processor ID (processor bus/local ID pair) completely.  As far as I
can see, but it's been awhile, so forgive me if I miss one or two,
IA64 doesn't expose the physical processor ID at all, outside the IPI
and AP startup code.

> The right approach to me seems to move everything including p->processor
> to logical and the few locations where needed otherwise (?) should
> be moved to have the translation from performed there.

Yep.  If not simply to make the generic kernel code clearer, this will
also make it easier to support non-linear (NUMA) systems.

--Walt
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