[PATCH] reorganized per-CPU data

From: Dimitris Michailidis (dimitris@cthulhu.engr.sgi.com)
Date: Fri Jun 16 2000 - 16:26:29 EST

From: Dimitris Michailidis <dimitris@engr.sgi.com>
Date: 16 Jun 2000 14:26:29 -0700
In-Reply-To: Andi Kleen's message of "9 Jun 2000 08:48:04 -0700"
Message-ID: <6yr66r9iagq.fsf_-_@darkside.engr.sgi.com>
Lines: 27
X-Mailer: Gnus v5.5/XEmacs 20.4 - "Emerald"

A new version of the PDA patch for data maintained per-CPU is available from

  http://reality.sgi.com/dimitris_engr/pda_patch-2.4.0-1.

New in this version:

- ported to -test1
- some more code has been converted to use the new scheme
- on MP systems we allocate only as many PDAs as we need.

Given that these structures are large (>2K each, larger with IPv6 enabled)
the allocation change above can save substantial space on MP systems. On a
4P box space savings amount to more than 79K, .text savings alone exceed 5600
bytes (including small savings in the system call and IRQ paths in entry.S ;-)

Andi Kleen wrote:
> Just an ugly problem is the Config dependent layout of the pda data
> and module binary compatibility. Maybe it would be possible to tag
> some magic symbol with its size and export it, making modules reference
> it ?

These issues are still present. I don't think exporting the size of a pda is
safe, you might be able to get the same size with different configurations.
Maybe exporting the offsets of optional fields? 

-- 
Dimitris Michailidis                    dimitris@engr.sgi.com

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